topic Re: Port blocking??? in Broadband

Port blocking???

Karlos1989 — Sun, 13 Jul 2025 09:34:33 GMT

Hi all,

I’m a web developer working from home, and I’ve recently encountered a persistent issue where I can no longer access MongoDB Atlas (a cloud database service) over my home Sky broadband connection.

Ive been trying to find an email address to submit a support ticket but i keep going in circles between virtual assistant and basic automated help pages...

Issue Details:

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- MongoDB Atlas is accessed over port 27017.

- My development laptop suddenly lost access, despite it working fine earlier in the day.

- The MongoDB website (https://cloud.mongodb.com) also won’t load from this connection so I can't even access my account or any of the **bleep** help articles.

- However, when I switch to a mobile hotspot, everything works perfectly — both the site and the database connections succeed instantly.

- This same issue occurred on my desktop PC a while back, which led me to stop using it for development — I now suspect this is a network-level issue, not a hardware one.

Tests I’ve Done:

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- I’ve tried DNS changes (e.g., Google DNS, Cloudflare DNS) with no effect.

- There’s no VPN or firewall blocking access.

- Traceroutes and port checks suggest the connection is being blocked or dropped by the ISP before reaching MongoDB servers.

- The issue only happens over Sky broadband — not on mobile hotspot.

Request:

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Could you please confirm whether:

- Port 27017 is being rate-limited, blocked, or shaped by Sky?

- There is a way to whitelist or enable this traffic permanently?

- Or, alternatively, if there are known restrictions on developer tools, cloud databases, or custom ports like this on residential connections?

This issue is interrupting my work and preventing me from completing important development tasks. I’d appreciate any assistance or clarification you can provide.

Many thanks in advance,

Re: Port blocking???

TimmyBGood — Sun, 13 Jul 2025 09:45:19 GMT

@Karlos1989 wrote:

- Or, alternatively, if there are known restrictions on developer tools, cloud databases, or custom ports like this on residential connections?

If you are using a white Max Hub then the issue may be IPv4 address sharing through Map-T.

https://www.ispreview.co.uk/index.php/2024/06/isp-sky-broadband-uk-deploying-ip-address-sharing-via-map-t.html

Re: Port blocking???

Karlos1989 — Sun, 13 Jul 2025 13:59:33 GMT

Thanks for the reply but no, it's not the max hub, it's an older one. SR203.

Is there maybe a similar issue with this one?

Re: Port blocking???

TimmyBGood — Sun, 13 Jul 2025 14:39:56 GMT

@Karlos1989 wrote:

Is there maybe a similar issue with this one?

No: the Sky Broadband Hub doesn't support Map-T.

Re: Port blocking???

Karlos1989 — Sun, 13 Jul 2025 15:11:09 GMT

So it's probably an ISP level port block or throttling? Or could it be something else? Maybe because I'm a residential customer so it's limited? I may need to switch plans?

Thanks for your help.