topic Re: Moved router using 15m cable between ONT and router - huge performance drop in Broadband

Moved router using 15m cable between ONT and router - huge performance drop

Kd104 — Thu, 04 Sep 2025 14:41:37 GMT

https://www.amazon.co.uk/dp/B09X2M4422?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1

As advised by Openreach engineer, we have ordered the above Cat 5e+ cable and fitted it.

We have a 300mbps full fibre connection, and this connection was being received by most devices. However, after fitting the cable and moving the router back to its original centralised position, devices are getting about 20mbps download and 50mbps upload each. [Specifically, gaming PC is getting 20 whereas before it was getting 250.]

The cable has been folded either end due to excess length.

Re: Moved router using 15m cable between ONT and router - huge performance drop

aac74 — Thu, 04 Sep 2025 16:24:17 GMT

I'd troubleshoot this by removing the new cable, putting the router back to the ONT on the short cable and restarting it.

Then check the speed the router is getting by signing into my sky here:

https://www.sky.com/mysky/broadband

and clicking on the 'run health check button'

If the speed and wifi look ok you can move on to the next steps:

Then restart your phone and install a wifi analyser on your phone like this one:

https://play.google.com/store/apps/details?id=net.techet.netanalyzerlite.an

And a speed tester like this one:

https://play.google.com/store/apps/details?id=org.zwanoo.android.speedtest

Make sure your phone is connected to your router wifi.

Move around the house doing speed tests and noting down the speed (from the speed tester) and the wifi signal strength (using the analyser tool - it is in menu > information > wifi details > signal strength).

The lower the signal number the higher the strength e.g. -25dBm is much better than -70dBm

This will give you an idea of what your speeds and wifi signal look like around your house, stronger signal should equal faster wifi speeds..

If this looks ok repeat the process with the longer cable and the router in the centralised position.

If you need stronger wifi in a room try upgrading to https://www.sky.com/help/articles/sky-wifi-max

or using a 3rd party wifi booster or mesh system.

Re: Moved router using 15m cable between ONT and router - huge performance drop

Chrisee — Thu, 04 Sep 2025 16:46:01 GMT

@Kd104 lay flat ethernet cable is not ideal but as it happens I have a very similar cable in my home which carries 500Mb/s without issue and probably could carry more. Standard ethernet cable has 4 twisted pairs and is therefore more resistant to picking up interference. I would not fold the cable instead have any spare in lose coil.

Difficult to advise but if you are getting 250Mb/s without issue the hub in its orginal position which is more than fast enough for gaming, streaming video etc.why move the hub?

Re: Moved router using 15m cable between ONT and router - huge performance drop

Kd104 — Thu, 04 Sep 2025 16:50:37 GMT

The original hub position is better in terms of range. Most of the upstairs is getting very poor signal when the router is next to the ONT.

Re: Moved router using 15m cable between ONT and router - huge performance drop

TimmyBGood — Thu, 04 Sep 2025 17:04:23 GMT

@Kd104

I'm somewhat dubious of that product description, because 'Cat6e' isn't a thing...

Cat5e ('enhanced') was a modification to the Cat5 standard: the equivalent in Cat6 is Cat6a ('augmented')

Re: Moved router using 15m cable between ONT and router - huge performance drop

aac74 — Thu, 04 Sep 2025 16:58:13 GMT

have you tried restarting the router and running a health check via the mysky website:

https://www.sky.com/servicechecker

To make sure the router is getting the correct speed.

Re: Moved router using 15m cable between ONT and router - huge performance drop

Kd104 — Thu, 04 Sep 2025 17:05:47 GMT

I have yes, the router is supposedly receiving its 300mbps. It also says wifi to devices are all good but that is far from true.

Re: Moved router using 15m cable between ONT and router - huge performance drop

Chrisee — Thu, 04 Sep 2025 17:05:49 GMT

@Kd104 a standard Etgernet cat5e or better cable should work as they can carry 1Gb/s up to 100m. As I said I use a similar flat cable to yours to link a wifi unit to my hub without issue but I haven't "folded it". It is never a good idea to bend any cable round too tight a radius as you can break the strands and flat cables can pick up interference so keep it away from mains cables or similar.

Re: Moved router using 15m cable between ONT and router - huge performance drop

Kd104 — Thu, 04 Sep 2025 17:06:43 GMT

Yes looking at it, it does seem SLIGHTLY perculiar, but the reviews seem genuine and not much reporting of poor performance like I am having.

I have unfolded either end now and they are just coiled.

Re: Moved router using 15m cable between ONT and router - huge performance drop

Kd104 — Thu, 04 Sep 2025 17:08:21 GMT

As I just mentioned, I have unfolded either end. They are now sitting in a loose coil.

The cable is not bent anywhere, and I would say there's a smooth curve no greater than 90 degrees at any point along the cable.

Re: Moved router using 15m cable between ONT and router - huge performance drop

Kd104 — Thu, 04 Sep 2025 17:17:15 GMT

I have a feeling that it is strictly the gaming PC and the consoles that are struggling here... The PC struggling the most, however it wasn't doing this before I installed the cable.

Looking at network settings on PC it's on 2.4ghz apparently, how do I keep it on 5?

Re: Moved router using 15m cable between ONT and router - huge performance drop

Chrisee — Thu, 04 Sep 2025 17:17:59 GMT

@Kd104 all I can conclude is that your cable is faulty in some way but its a strange fault as if it passed 90Mb/s that is explicable but 50Mb/s is not easy to explain.

Re: Moved router using 15m cable between ONT and router - huge performance drop

Kd104 — Thu, 04 Sep 2025 17:19:00 GMT

Apologies, just sent another reply.

My mobile devices are in the same room as the gaming PC getting 20mbps, running a speed test and getting 250+mbps.

Any ideas?

Re: Moved router using 15m cable between ONT and router - huge performance drop

Chrisee — Thu, 04 Sep 2025 17:24:28 GMT

@Kd104 PC wifi cards can need updated drivers so check the network settings. If the PC is reasonably close to the hub use a second ethernet cable especialy if you plan to play games.

Re: Moved router using 15m cable between ONT and router - huge performance drop

aac74 — Thu, 04 Sep 2025 17:24:40 GMT

Clearly the wifi signal is fine, it is the PC that is the issue!

On the PC:

In admin command prompt:

Type ipconfig /release and press Enter.
Type ipconfig /flushdns and press Enter.
Type ipconfig /renew and press Enter. (This will stall for a moment.)
Type netsh int ip reset and press Enter. (Don’t restart yet.)
Type netsh winsock reset and press Enter.

Then reboot.

Re: Moved router using 15m cable between ONT and router - huge performance drop

Kd104 — Thu, 04 Sep 2025 17:28:58 GMT

Hasn't done anything I'm afraid.

Re: Moved router using 15m cable between ONT and router - huge performance drop

Kd104 — Thu, 04 Sep 2025 17:29:59 GMT

No chance of an ethernet connection unfortunately. But have managed on wifi for over a decade.

Wifi card drivers were updated again today to OEM

Re: Moved router using 15m cable between ONT and router - huge performance drop

Kd104 — Thu, 04 Sep 2025 17:31:28 GMT

Upload speed is fine.. download remains terrible. [worse than my copper line was]

Don't know why.

Re: Moved router using 15m cable between ONT and router - huge performance drop

cookiemonsteruk — Thu, 04 Sep 2025 17:39:48 GMT

@Kd104

Take a look at anything else downloading at the same time. That ping of 216 fully loaded looks excessive for a speed test.

My 100mbps connection unloaded has a ping of 5ms and 17 ms loaded . Also note that when your ping went down the speed went up a wee bit

Re: Moved router using 15m cable between ONT and router - huge performance drop

Kd104 — Thu, 04 Sep 2025 17:55:41 GMT

There are no devices doing anything at the moment, so it's not that.