TCP connection pauses

[#1]

I'm having an issue with Plusnet Fibre Broadband and the Hub One. For TCP connections (this noticeably affects SSH, HTTP/HTTPS), connections just seem to pause periodically. For example, I can be connected over SSH from a PC behind the router to a web server, and after a period of time, both sides will not be able to talk to each other for a period. For TCP, this means that both sides build up a send-q until eventually everything just starts flowing again, and the queue clears. This might sound like the router Internet connection is going down, but this is not the case as ICMP pings work throughout with 100% success. I've done several tests, and this issue only seems to affect TCP.

On HTTP/HTTPS it's most obvious by pages failing to load and then timing out and needing to be refreshed. It's quite frequent and frustrating.

Is there an issue in the router's connection tracking that causes this sort of horrible behaviour? Or is there something going on in Plusnet's network? With the recent push to protect the eyes of children, I presume ISPs have built up a complicated system for filtering, and I wouldn't be surprised if something could go wrong with that.

All of the safety features are turned off on the account; SafeGuard, Surf and Broadband Firewall. I've left the router with default settings to allow all out and block all in.

Is there an email address for support? I don't really want to spend a long time on the phone.

[#2]

Do the router logs tell you anything? Are you able to packet capture this happening using something like Wireshark?
I've run (and connected to) myriad servers from my PN connection in the past whilst using a Hub One, and never encountered issues

[#3]

Hello,

I've been playing around and doing a few tests, but I believe the problem occurs when my computer switches from 2.4GHz to 5GHz and vice versa. It's almost as if the device doesn't recognise I've changed to the other radio until something times out.

I could be wrong though; I'm just basing this on the fact that if I tie my computer to the 5GHz connection (I specified to only connect to the specific BSSID), then the problem goes away.

Anyway, posting this here in case anyone else has similar issue and want to try this.

Cheers.