If this happens for all internet access/multiple games, first thing to rule out would be things like new firewall/internet security settings or any changes to your router. You could also try going through the process of completely disconnecting and rebooting your modem and router (with both the permission of the hardware owner and using the steps provided in the manuals by the manufacturers).
On the other hand I had something similar happen myself with another game. It wasn’t to do with my connection at all (SpeedTest.net confirmed this) even though seemingly the most obvious symptom was really high latency in lobbies and terrible lag in-game (600-1500). The reason for me was that my PC was pretty old and something somewhere had given up. I rebuilt my PC (it was about time) and the new hardware didn’t produce the same issue on the same internet connection and router setup.
Obviously a full rebuild upgrade isn’t always possible, in which case you’ll need to swap in/out all the parts in your PC until you find the issue. If your PC is still under warranty I’d send it in for repairs first before opening the case, as this usually invalidates your warranty. If you’re not certain about PC maintenance, seek advice from your supplier before attempting anything.