All since gamerspy went bust Crysis Wars online support has been dead. But this fairly short guide will set you up against the few others who still plays Crysis Wars online.

http://germancrysis.com/viewtopic.php?f=2&t=1631&p=22605#p22605

Follow his instructions carefully and you should have no problem. There aren't that many people playing it (most likely the majority doesn't know that they still can) but you'll find people going about during the weekends. And a few during the work days.

Addendum: I would like to mention the author of the guide also provided a guide to get the excellent mod MechWarrior: Living Legends to work. Although I'm sure it still work it's a bit outdated. All you need to get the mod working is within this link (you don't even need Crysis Wars installed to get the mod to work) . So if you like mechs and tank fighting, why not check it out? It's free :)

https://clanjadewolf.net/mwll/