So this is how it went:
Thursday: Installed oRA2 and PallyPower, since my new guild required those. Raided 19:30 - 23:00, ICC25 first, downing 10 bosses, then VoA25. No problems at all.
Saturday: Updated every addon through Curse Client (which i haven't done in some time,but and reworked my UI a bit, without adding anything new to it (except for a few textures imported to kgpanels). Still no problems.
Sunday: Raiding 20:00 - 23:00. Starting at Sindragosa 25, i DC a few times before we pull her, but my latency was also very high (2k+ ms) i assumed it was just something with the internet being unstable (which never happened before). I was a bit laggy on the first attempt (wipe on 2%), after that it was fine, and we downed her on the next try.
While standing on LK's platform the RL explaining what to do, i suddenly don't hear him. Every other sound is fine (like WoW's) but i don't hear anything on vent, even though i see that they are talking. After 1-2mins, it's working again. Then the same thing happens, but this time i fix'd it by restarting vent. No more problems with vent after this.
At around 22:30 my latency starts to rise again, and after a few mins it's around 2k like on Sindragosa's trash. I DC a few time as well, but i still thought it's just the ISP having a bad day. At the very end though (like 22:50) I start to chain-DC, and every time i logged in i instantly DC'd. After 3-4 attempts at buffing but DCing, the RL decides to do the last go on LK without me. I log my druid, to see whats up, and to my great surprise, i don't DC there. I'm standing in dalaran with the usually 150-200ms latency for a few mins, without any problems. Thought it must've been the internet being unstable, i log back to the pally, and instantly DC. Logged out, deleted Cache, and restarted the computer. When i logged back onto the pally again, there was only a few people left in the raid group, and i was standing at the Light's Hammer, but it seemed to be stable. Ported back to dalaran and talked a bit in /g before going to sleep, and i had no problems during that time.
Monday: Did the random battleground and heroic without any problems and logged off. Logged back, and since i wasn't taken to the raid, i did random battlegrounds. Around 21:45 i join the raid as replacement and after a few attempts on LK, the same thing happens; latency slowly goes up to 2k-ish, DC, i try to log back, instant DC, try it again, instant DC again. So i logged off, deleted Cache and didn't instantly DC after that (this was at the very end again). So after the raid i stay in ICC talking with another pally in the guild, and i only DC once during that, but i can log back without problems.
Tuesday (yesterday): ICC10 semi-pug at 14:00. Joined the raid group around 13:15 and was doing random BGs until it was full. DC'd once when i started flying to ICC from Dalaran, but i could just log back without problems. While buffing it did it again, latency going up, and the chain DCing. Logged off, deleted cache again, and restarted comp. Also, when i logged in i disabled every addon except Grid, SUF, Bartender and Satrina's Buff Frames. We downed 5 bosses, and i only DC'd three times, once on the trash before Lootship, and once on Plaguequarter trash.
When i logged back quite late, around 21:00, i was standing in daralan, queued up for a random battleground, and DC'd as soon as i zoned into AV. Relog, instant DC. Close down wow, and this time i deleted the cache, wtf, and interface folders. Thought it was alright, as i went from dalaran to SW to buy raw gems without DCing, and even queued up and zoned into IoC without problems. But after a few minutes, i DC'd again...
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Also, some of the DCs were not just a disconnect, but the screen froze and i couldn't even Alt Tab out. The only way to do something else was to Switch Used in windows with the Windowskey+L and the log back. It returned me to the desktop with WoW minimized so i could do other stuff, and after a while i heard the login-dragon's roar, Alt Tabbed back and it was on the login screen with the usual Disconnect message.
Since i have no idea what's causing it, or what i could do to fix it, i'm starting look something like this:
Any kind of help would be greatly appreciated.
Wall of Text crits you for over 9000