Friend from another country can not play with me

[Tetromiko]

My friend is very laggy when we playing together, like warping every 2 seconds, and he always gets messages like "server is not responding", by that way another friend feel free and out of lags, but he lives in one country with me, you can say "it is obvious - bad internet connection", but I say "maybe, but explain that thing" - when I started server for the first time, he got no lags, maybe some freezing sometimes, but on our second session it just can not be playable anymore for him, difference is massive.