Okay, managed to narrow this down quite a lot but still not got the solution.
When I was first having issues I went in to cmd prompt and did a socket reset. Restarted the machine and all seemed to be good.
I then reinstalled the driver and again everything fine.
Then I reinstalled Windows. Its been s*** ever since.
It connected wirelessly when I reset everything. But it would start okay, slow, then cut out.
I then ran the troubleshooter, it did its thing. Fixed the default gateway, and a few seconds later after initially looking like nothing had been fixed, it connected and would work. Then cut out in the same way after. Times for this varied.
I tried resets in cmd - sockets & int ip. release ipconfig. renew ip config. flushed dns. Not fixd it.
I then brought it downstairs and hardwired it. Worked perfectly and was getting 102mbps. For ref laptops get max 50, av. 40.
I then tried to connect wirelessly. About a metre away from router. Same issues. So doesn't seem like a distance/interference issue.
Ran troubleshooter, fixed, connected. Then ran a speedtest. It was getting 70+mbps (so the card must be better than my laptops) before speedtest stopped working - Socket Error.
Did the same troubleshooter fix, connected. Ran Speedtest again. 70+mbps. Fail. Socket error.
This socket error on speedtest occured all 3 times I tried and it seemed it was at the end of the download test/beginning of upload.
I've also recieved socket errors sometimes when Chrome fails to load.
However I've mainly get errors in chrome. Usual fix in troubleshooter is bad gateway.
Searched all this online and amongst a few suggestions of causes was corrupted registry entry.
Tried to fix this using startup fix in Windows but it said 'Windows couldn't fix the problem'. Now whether that's because it can't fix that unspecified registry error, or because there were no errors, I don't know. Strange message to get mind on a very general option.
Still having same connection issues.
Gave up.