Odd internet issues.

[Joel_M8]

Hi all

I've been in contact with BT twice over the phone regarding this issue. And neither operator was able to help me fix this it.
My internet has been behaving very weirdly. My router and modem show no sign of it cutting out, the lights remain normal, but my phone will say its "connected without internet", I can't load any new pages on my PC, open images/videos, etc. 
But for some reason a live stream will continue to play if I have one open. If I'm in a discord call, I won't be kicked out and my friends can still hear me fine. When a full connection returns, there's no lingering issues and my speed is never throttled. It's almost like its only half disconnecting?

Again I have been on the phone to two BT operators who ran every check they could, but they turned up nothing, no problems with my router, line or any signs of it cutting out. Fibre experts apparently suggested that I be sent a new ethernet cable to connect to the modem as I'd had the current one for over two years, but the issue is still persisting after receiving and connecting it.

My knowledge with tech is pretty basic, I'm at a loss and not really sure where to go from here. I would rather not sit on the phone for an hour again only to be given the same answer and potentially be sent another new piece of tech that likely (knowing my luck) won't solve the issue. I was also told that, if an engineer were to be sent out, they would also just tell me there's no issue.

For those wondering.
Yes, I've done a full power reset and one of the operators ran a factory reset.
My package is Full Fibre 500 and I've been on it since April 2024 with no issues until now.

Would be great if someone could give me a hand here.
Thanks!

[WSH]

Certainly sounds like a intermittent cable connection.

When you changed that ethernet cable to the ONT did you just connect it the once or a few times (to polish the contacts)?

How is your equipment connected, wired or wireless?  If wired, try reseating the cable as I've just described.

[shakey1981]

check the router log for disconnrctions

[licquorice]

It's not a physical connection problem or your working connection would disconnect. It appears to be DNS resolution problem, I e new connections are not being resolved. Not sure how you get BT to investigate though.

If you haven't already done so, try a full factory reset of the hub using the reset button rather than just a power cycle.

[Joel_M8]

The ONT cable, I connected once and have left it since then. I wasn't aware about a method with polishing the contacts, I'll try it out when I get the chance.
My PC is on a wired connection, as are my two consoles (they don't get used much).

[WSH]

It could be any one of a number of things and the full factory reset suggested is a good idea too.  Just remember that will clear any custom settings you've made, so I'd export the configuration first and then you can reimport it afterwards.

It's a strange one but it reminded me I have once seen a problem with the connector in a socket that was causing one wire to drop out and the connection to keep flicking between 100Mb/s and 1000Mb/s.  The auto-negotiation that triggered was making the connection freeze for a second or two but not drop out.  I cleaned it it was fine ever after.