I have arma 3 apex and cant join any servers with direct connect.

I'm not entirely sure what may / may not be causing the problem, but; I do have a suggestion from a steam post that you should try.

Note: Before you start you’ll need an IP address of a public server that you’ve played on in the past.

Step 1: Log out of Steam and go into “Offline Mode”
Step 2: Launch Steam in Offline Mode”
Step 3: Launch Arma 3
Step 4: Go to Multiplayer
Step 5: Select Direct Connect
Step 6: Enter the IP address of the public server you’ve played in the past
Step 7: Join the server – Note When I tried this I didn’t get the connection failed error, I just got a picture of the Tanoa map. If you get this far then processed to the following steps.
Step 8: Log out of Arma 3
Step 9: Turn Steam back to “Online Mode”
Step 10: Launch Arma 3
Step 11: Go to Multiplayer
Step 12: Go to Direct Connect
Step 13: Enter the IP of the public server

Reference - https://steamcommunity.com/app/107410/discussions/0/365172547956160802/