friends can't join server

Same here. Two players from Poland and one located in Sweden can't join each others' games at the moment, regardsless of which of them is hosting. 'Server Not Responding' shows up.

Same here. I can join my friend server with invite but they can't join my server same method. She said server not responding. Also normally when I open custom match, I can't see anyone try join my server too. (public and without password) Maybe its about port issue, I don't know if there is a need of special permission or something else. Steam should handle the server issue since it works online.