There were a lot of threads on this matter, some very long. We’ve never received any confirmation they’re aware of the issue or are looking into it - if it happened on US realms then sure, but EU? Guaranteed to be left w/o a response.
I’ve had this issue since ealy February, so over half a year now, and it still persists. And Blizz ignores the issue entirely despite quite a few folks having to deal with it.
You can try using PingPlotter to narrow down where the hiccup occures. For the vast majority of people with this issues it happens here (marked):
https://i.imgur.com/5vZsAD6.png
So there’s that. You could try using paid VPN (Vietnam, for instance) to circumvent this problem - worked for a handful of lads. But using a paid VPN in a game having a subsciption model that requires buying expansion packs… yeah, nah. Not paying three times for that. No other games have this issue, and if they had it was fixed within hours / days. Blizzard got time though, and waving their middle one at their customers for half a year is hardly surprising at this point /shrug
You can check this thread for some data you might find useful: