Your browser sent a request that this server could not understand

My browser forgot how to talk to servers? :) After the struggling with the typing issue yesterday, today I got a new one. Some https website doesn't come in. Not all, Google for example works but mxhomepro.com from URC does not. DNS flush, deleting cookies, re-registering some dll... Still nothing. Running Antimallware found some registry issues, quarantine them. Restart... And all good. Still don't know what was that, maybe some commands yesterday, what I run in Terminal and PowerShell? Misery...