Hello, having the same problem. I tried the Pingplotter tool, to check, were are the packed lost and found out, that my packets are going through an MPLS Router in Frankfurt, Germany and he is the problem.
You can check the tool via this link:
https://eu.wargaming.net/support/en/products/wot/article/10252/
But no idea how to fix it as I am not from Germany and my ISP provider cant help as the internet connection is stable.