I accidentally sent a mail thinking this was a reply for my previous mails, whoops.
I’ve done what you said and also disabled the 5GHz connection from my router, as I suspected it had something to do with it.
So far it’s all looking good, though I’m not able to use my 2,4GHz connection anymore. As I said eventually the problem appears again, I’ll see if these things fix it.
If anything happens I’ll write again.