Ubuntu 18.04 LTS wifi problems
FINALLY. I can confirm that since two years I finally fixed my wifi problem. The solution was actually super easy and near to me: I had to change REGDOMAIN in crda (I had there different country code):
sudo -H gedit /etc/default/crdaREGDOMAIN=<YOUR COUNTRY CODE>reboot (mandatory!!)
You can take your country code from here.
To sum up, I'm using bcmwl-kernel-source wl driver for my Broadcom BCM4352 card. (good info/tutorial about it is here). I still receive sometimes those errors and have few small timeouts for ~1 second (no disconnects!), but I think it's natural and it doesn't bother me compared to what I had before...