Same problem here.
In the last few years (since the very beginning from premier) i used the same ISP and had no problem. Even when we transferred to the Steam. But, after the last content patch in tuesday, i cant play anymore. Or, at least barely - fortunatly, I have two ISP service at my home (One, for my family and one for my work).
When i connect with the regular ISP (type: cable, ISP name: MVM NET (a country sized local ISP in central Europe, i used this in the beginning)), i get a "unable to initialise network, check..." error after i hit the play button in the launcher. I can play every mmo and other online games, except the Elite
When i switch to another ISP (type: wifi, ISP name: DIGI (a region sized ISP in middle Europe)) everything is fine, and i can play.
Firewall is okay, firewall/security system's exceptions are okay, my system is okay, everything works fine. Reinstalled the game, checked the files integrity from the launcher, then from Steam, tried to launch with the .exe, etc., nothing helps, only when i switch to another internet connection
(sorry for my bad english, tried my best)