Suddenly High Ping for no reason

Ive been playing on Blackrock/arena-tournament for like 4 years now and always had a good ping from 20ms-50ms. For like 2 weeks now suddenly my ping is completely crap and fluctuating between 200ms and 2000ms. In short - there is no way for me to play on this server anymore. If anyone has a solution to this weird problem that would make me very happy.

edit: I thought i add some description to the "bug"
When i cast something ingame then sometimes the spell is instantly casted and sometimes the spell takes like 1-2 seconds to cast. Seems like the latency is changing rapidly constantly for whatever reason.

edit2: Still need help...

edit3: Problem solved. The router was broken. Exchanging it with another one solved the problem.

have you already tried some SpeedTest to see if the problem is your connection? if you didnt try here http://www.speedtest.net/ the Server (blackrock) is located in Paris so you can try the speedtest with that city

My internert connection should not be the problem. I have already tried all kinds of speed and pingtest. I even pinged the Blackrock server (its ip should be 37.187.174.57 right?^^) with with cmd and also with a programm called PingPlotter. Even after pinging the server 200 times my ping was never worse than 30 ms. Not to forget that no other game is affected by that. Only WoW. I guess that its a problem between internet providers and that i can do nothing about it.
bonus screenshot: http://imgur.com/FkVwJzT

But thanks for your help anyways:)

First time I see a Connession with Upload higher than Download, eheh.
mmm try to use Google DNS
Do you have this problem wiht only 1 Char or all Blackrock Chars?
Try to play on the other Wotlk Realms and see if even there you have high ms ( just click on Change Ralm in the Blackrock Characters List)

Yes the problem is the same on all wotlk servers. All chars are affected. Using google dns didnt do anything. I guess i try another wow private server just to test if this problem could be my WoW version or my computer. Any advices for another pserver i could test on?^^ If everything works fine on other private servers i guess the solution of this problem is not in my hands and lays somewhere between my internet provider and their computing centre.

actually warmane has also Cata 4.3.4 and MoP 5.4.2 realms so you can try on them But if you do not have these clients you can downlaod them from here https://www.warmane.com/download
Maybe at that point you can just try to download a new Woltk client from that page ( download the Wotlk "Old" from there, the "Not Old" has WoD Model and sometimes it causes problems)
I hope someone with some knowloadge about this kind of "connecting" bug can help you