[Disconnected from the server] constantly and randomly! Very annoying

Hello!

For the past month or two, I have been having a very inconvenient issue.

Randomly I get disconnected from the server, usually at very inappropriate times. Often during boss battles in raids which is REALLY bothersome. The screen just suddenly freezes for a few seconds then [Disconnected from the server]. I usually can log right back in, but during raid boss battles I get sent to the entrance of the raid instance!!!!

I recall trying many things - changing some files, setting to Read Only, etc. Even setting display settings to low quality.
I have plenty of addons, but I believe there are many people who have similar amount of addons as me - or even more.
But the issue persists... my internet connection isn't the best, but I don't think it disconnects so often. When I browse other websites or games, they work just fine. My internet doesn't seem to go down that often.

Please, can someone help me? This problem is VERY annoying and I can't just keep being cut off raid boss battles like that :/

I want to raid properly. Yesterday I was in mid BQL and I dced - when I log back in, naturally, I get all the way back to the entrance of ICC (and that wasn't the only time I dced during that raid!). 10 minutes ago, the same happened in VOA25 and I couldn't even see what dropped from the boss. I keep missing achievements and loots because of this extremely annoying issue!

Thank you VERY much in advance!

Realm: ICECROWN. In all of my toons