So it turns out there are some routers that have problems with the DR server.
Taken from this old forum post, it turns out that the problem is how the router handles UDP packets.
DR wants to use Loose UDP packets, most (newer) routers think of this as a security risk and drop those packets.
It’s quite technical, read the article if you want more detail. The point is that we cannot fix this with a patch, as it is router specific. If you are having problems (eg. seeing people in the lobby with 2000ms pings, not able to join games, not able to some other people speak) then do the following:
1) Turn off all firewalls, both on windows (including the default one) and on the router
2) Try activating DMZ (Demilitarized Zone).
3) Try enabling the ‘loose udp’ option on your router (sometimes known as ‘gaming mode’)
4) Try searching google for your router and loose udp or udp packets in case there is a firmware update, or a different method of enabling loose udp or someone had the same problems.
5) Finally, there’s nothing you can do, your router is just incompatible with DR, time to upgrade?