On demand download failure Sky+ on 2 boxes

[emteepeeess]

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@pkjp wrote:

Just a thought - has anyone tried flushing the DNS cache on their router?

Unfortunately, I think most of the time this would probably need to be done by performing a (factory) 'reset' on the router (so, you may want to note any ISP connection/configuration/SSID details before doing this in order to be able to connect again).

Sky have admitted to changing their infrastructure that then required them to amend their related DNS entries to point to their new server(s). For this to work, it needs any new download request from a user's sky box to go to a DNS server to get the latest IP address. Normally, a DNS lookup would only maybe be performed the first time you request access to a particular server. After that, your browser and/or router may cache that entry to save time on the next request. If the router has already cached the old DNS entry, this may explain why some routers are struggling to get the new DNS information - it's just going to the local router cache instead (which then resolves to the old and wrong IP address). It also explains why new routers or phone hotspots also work  - they won't have the same cached information.

Eventually, the local router cache should be refreshed (as it only has a certain life span) at which point any request will go to a DNS server and get the latest IP address. This is probably Sky's 'fix' - they're just waiting for each user's local router cache to expire. 

Might be wishful thinking but possibly worth a try for anyone not wanting to buy a new router.

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This will apply to Sky boxes that have the router as their DNS lookup source. What about Sky boxes that have the DNS server set in the networking set-up? Surely they will bypass the router.

Mine is set to 8.8.8.8 (Google's public DNS), although I've tried different setups to no avail.

[emteepeeess]

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@Annie+UK wrote:

@thegfb From the evidence I have seen, Sky changed a servers IP address and sent the new address to the DNS servers around the world, companies do this all the time as have I in the past for my own web server, this has highlighted that some customers routers have not updated to the new IP address correctly, how on earth can you hold Sky responsible for hardware and DNS server updates outside their control? or do you think that changing a server IP corrupts peoples Internet hardware?

Disclaimer: We have not had 100% cofirmation of the entire issue so the above is using the info we have thus far

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Changing the IP address across DNS servers is done, as you say, on a regular basis, and routers will normally pick this up very quickly - after all, if a news site's new IP address doesn't get picked up quickly then people would quickly notice.

DNS servers deliver the IP address with a TTL (Time To Live) value - IP addresses that rarely change are typically set to 12 or 24 hours, frequently-updated sites may go as low as 5 minutes (less than that is not advised).

But it is possible to set the maximum TTL as 4,294,967,295 seconds, and some sites accidentally do this! The result is that the client never checks to get a new IP address unless the client does a manual purge. 

So, if Sky accidentally set an extended TTL on a CDN (Content Delivery Network) server's IP address at one point, unless the Sky box purges its cache (if the user has set the Sky box's DNS setting to an external DNS server, like Google's 8.8.8.8) , or the router does so (or changes the router) then they'll be locked out.

And I can tell you that for at least one online platform, exactly this has happened!!

Of course, PCs and many routers have the ability to purge the cache, but is there a guaranteed way of doing this on the Sky box.

Now, of course, some routers may flush their caches regularly (but it isn't a requirement). 

[pkjp]

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@emteepeeess wrote:

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@pkjp wrote:

Just a thought - has anyone tried flushing the DNS cache on their router?

Unfortunately, I think most of the time this would probably need to be done by performing a (factory) 'reset' on the router (so, you may want to note any ISP connection/configuration/SSID details before doing this in order to be able to connect again).

Sky have admitted to changing their infrastructure that then required them to amend their related DNS entries to point to their new server(s). For this to work, it needs any new download request from a user's sky box to go to a DNS server to get the latest IP address. Normally, a DNS lookup would only maybe be performed the first time you request access to a particular server. After that, your browser and/or router may cache that entry to save time on the next request. If the router has already cached the old DNS entry, this may explain why some routers are struggling to get the new DNS information - it's just going to the local router cache instead (which then resolves to the old and wrong IP address). It also explains why new routers or phone hotspots also work  - they won't have the same cached information.

Eventually, the local router cache should be refreshed (as it only has a certain life span) at which point any request will go to a DNS server and get the latest IP address. This is probably Sky's 'fix' - they're just waiting for each user's local router cache to expire. 

Might be wishful thinking but possibly worth a try for anyone not wanting to buy a new router.

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This will apply to Sky boxes that have the router as their DNS lookup source. What about Sky boxes that have the DNS server set in the networking set-up? Surely they will bypass the router.

Mine is set to 8.8.8.8 (Google's public DNS), although I've tried different setups to no avail.

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The Sky box outgoing request must pass through the router. I doubt the Sky box can focibly bypass the router's local DNS cache (if present).

[MogwaiSatTV]

I have tried changing the DNS on the Sky box to Google DNS and Cloudflare which has not helped. I also changed the DNS servers set on my router to use Google DNS rather than Plusnet's and that has not helped either.

What I am trying to findout is what is changing when people switch routers that then makes this issue go away. Is it just that the new router has a different MAC Address. As it does not seem to just be that changing routers means a different ip address is then assigned, as I have had Plusnet give me a new static ip and that has not resolved the issue. If it is the MAC address of the router then it seems I could change it to a new mac address.

[PocketDog]

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@MogwaiSatTV wrote:

If it is the MAC address of the router then it seems I could change it to a new mac address.

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Certainly worth a try if you can 👍  (I would give it a go but Im at work until late)

[pkjp]

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@MogwaiSatTV wrote:

I have tried changing the DNS on the Sky box to Google DNS and Cloudflare which has not helped. I also changed the DNS servers set on my router to use Google DNS rather than Plusnet's and that has not helped either.

What I am trying to findout is what is changing when people switch routers that then makes this issue go away. Is it just that the new router has a different MAC Address. As it does not seem to just be that changing routers means a different ip address is then assigned, as I have had Plusnet give me a new static ip and that has not resolved the issue. If it is the MAC address of the router then it seems I could change it to a new mac address.

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It shouldn't be related to your MAC address as DNS servers shouldn't care about that. What would be different on a new router is the local DNS cache (for example, if the router was new, the cache would be empty). This local DNS cache in your router is different to the DNS server IP you set on the Sky box and the DNS server IP you set in your router. Instead, it's just your router caching the result of any DNS lookups previously made to DNS servers and storing that result in local memory to save repeating the same DNS lookup again the next time.

[PocketDog]

So would turning your router off for 30 seconds or more flush the router's DNS cache? 

A few posts on the web suggests it would.

That didnt help when I swapped to a different router for a few hours (solving the issue), as when I had to go back to the old router, the download problem came back. 

[pkjp]

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@PocketDog wrote:

So would turning your router off for 30 seconds or more flush the router's DNS cache? 

A few posts on the web suggests it would.

That didnt help when I swapped to a different router for a few hours (solving the issue), as when I had to go back to the old router, the download problem came back. 

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No, I think it would need to be more substantial like a factory reset of the router. Like I mentioned in my original post, I haven't tried this - it's just a possibility but worth a shot if you don't have a spare router or don't want to buy one.

[Steve0001]

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@pkjp wrote:

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@PocketDog wrote:

So would turning your router off for 30 seconds or more flush the router's DNS cache? 

A few posts on the web suggests it would.

That didnt help when I swapped to a different router for a few hours (solving the issue), as when I had to go back to the old router, the download problem came back. 

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No, I think it would need to be more substantial like a factory reset of the router. Like I mentioned in my original post, I haven't tried this - it's just a possibility but worth a shot if you don't have a spare router or don't want to buy one.

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Yes.

It would be of great help to those of us that haven't bought a new router to have those that have bought a new router (and have it successfully up and running for downloads) to plug the old one back in and do a factory reset on it. It would be a pain to set the connections back up to your ISP on a factory reset router but if it fails you can always just plug your new router back in (which you know works).

If a factory reset works on your old router then that would help a lot of us as it would give us the confidence (or hope?) to try it on our routers for which many of us do not currently have a backup.

[MogwaiSatTV]

I have tried the Bypass DNS Cache option that my router has and that has not helped the situation. So I have emailed the support desk for the router manufacturer to see if there is another way to flush the DNS.

[emteepeeess]

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@pkjp wrote:

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@emteepeeess wrote:

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@pkjp wrote:

Just a thought - has anyone tried flushing the DNS cache on their router?

Unfortunately, I think most of the time this would probably need to be done by performing a (factory) 'reset' on the router (so, you may want to note any ISP connection/configuration/SSID details before doing this in order to be able to connect again).

Sky have admitted to changing their infrastructure that then required them to amend their related DNS entries to point to their new server(s). For this to work, it needs any new download request from a user's sky box to go to a DNS server to get the latest IP address. Normally, a DNS lookup would only maybe be performed the first time you request access to a particular server. After that, your browser and/or router may cache that entry to save time on the next request. If the router has already cached the old DNS entry, this may explain why some routers are struggling to get the new DNS information - it's just going to the local router cache instead (which then resolves to the old and wrong IP address). It also explains why new routers or phone hotspots also work  - they won't have the same cached information.

Eventually, the local router cache should be refreshed (as it only has a certain life span) at which point any request will go to a DNS server and get the latest IP address. This is probably Sky's 'fix' - they're just waiting for each user's local router cache to expire. 

Might be wishful thinking but possibly worth a try for anyone not wanting to buy a new router.

---

This will apply to Sky boxes that have the router as their DNS lookup source. What about Sky boxes that have the DNS server set in the networking set-up? Surely they will bypass the router.

Mine is set to 8.8.8.8 (Google's public DNS), although I've tried different setups to no avail.

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The Sky box outgoing request must pass through the router. I doubt the Sky box can focibly bypass the router's local DNS cache (if present).

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Yes, of course it passes through the router - but an IP address will skip the router's domain name resolution to an IP address as there's no need as it's already an IP address. This will then send the DNS request to the requested remote DNS server which, in our case should return the IP address of the CDN being used.

The only time that the router should intervene is to determine if the IP address is on the LAN or the WAN so it knows in which direction it should route the packets.

[emteepeeess]

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@MogwaiSatTV wrote:

Is it just that the new router has a different MAC Address. ...  If it is the MAC address of the router then it seems I could change it to a new mac address.

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As someone pointed out, the MAC address is not used  in WAN IP routing

What I am trying to findout is what is changing when people switch routers that then makes this issue go away. 

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I can really only think of two reasons:
1: the "problem" router has had its DNS table corrupted by Sky inadvertently setting the Time To Live parameter too long, and it stubbornly refuses to resolve the domain name into an IP address - the new router doesn't have this problem (either it never got the bad TTL or doesn't have the URL in its table)
2: The protocol being used by Sky is marginal on the spec, and some routers are more forgiving than others

Whatever the problem there's a 90% certainty in my view that the problem is with Sky and not with us (despite comments earlier). 

I've spent most of my working life diagnosing technical problems including, in later life, network issues. I don't believe that Sky has been suitably pro-active on this, and a lot could have been done by Sky network specialist visiting two or three affected households and analysing the situation using network tools and their understanding of exactly how their system works.

[MogwaiSatTV]

@emteepeeess I have kind of done that last part for them already as by using switch with port mirroring I have given them a Wireshark trace which they agreed they could see "anomolies" in.

[Eddy99]

@Steve0001 If a factory reset works on your old router then that would help a lot of us as it would give us the confidence (or hope?) to try it on our routers for which many of us do not currently have a backup.

Hi Steve, i drew the short straw and have just tried this now for the purpose of the test, it did not work i am afraid, was hoping for a positive result.

I swapped my newer router with my old router the other day and got up and running again. I just did a factory reset on the router Sky does not like anymore and still had the issue with downloads after a full reset.

[AliDun]

@Eddy99 thanks for trying that, saved some of us a lot of bother for no result. Much obliged.