I also created a ticket with this same issue before
http://feedback.arma3.com/view.php?id=1296

I am no longer able to reproduce this bug reported earlier. This particular connection issue does not exist in the latest game build.

Having switched routers, the problem no longer exists.

Likewise with a Thomson, I cannot successfully connect to a match beyond the role assignment screen.

Having switched routers to a DLink, the problem no longer exists.

It appears in this thread that many are having issues with "Thomson" routers and the inability to enter multiplayer matches successfully

I've tried numerous slots that were UNfilled and I appreciate your help ... slots were with and without AI enabled. I believe it's an issue with ports and UnPn

@xRupture I can't select a class on 99% of the servers I have tried ... and I can no longer find the 1% that previously worked. I made over a dozen attempts. I also disable the security features via the modem configuration. Darn Thomson

I have a Thomson router and I cannot select the roles/class on any server. I remain stuck in the pregame menu with my name highlighted gray.