Tech help

This is in fact related to CoW, but I wasn't sure where it belonged so I settled on here as the least disruptive spot.

So, lately I've been sitting out of games because I've been getting this message:

Which, when I play a game, means it's insanely laggy and automatically on the low-graphics mode (the latter I can live with even though I find it ugly but the former is such an impediment that I actually abandoned a game because it was annoying me so badly).

I've tried clearing my browsing data, including cache. Nope. In fact I tried that again just before posting this just in case I didn't remember to clear everything last time, and achieved nothing.

I've also tried moving to places in my house where there's better internet, because the room I'm usually in is awful from that perspective, just in case that makes any sort of difference. It doesn't.

Since I am not a tech person, this represents the limit of my troubleshooting abilities, so: has anyone else had this problem, and how did they fix it (if indeed they have)?

I've actually had this for over a month now, and I've been hoping it would clear up by itself, but now I'm considering joining the forum game but really don't want to play with the mobile version, which I have tried and hate almost as much as the laggy monstrosity desktop has become. And switching to a different PC is not impossible but highly impractical. So this has suddenly become more urgent.