We have an issue after standing up a hybrid solution. Only on-prem users can see online users and send messages. Does not matter if they are local to network or coming through Edge server on guest network. Online users can only see other online users, cannot send or reply to on-prem users. Both sides are open federation. Federation partner test passes. All users are synced with AADC with Skype attributes enabled. All local, tenant configuration settings, DNS entries doubled checked by multiple people. Edge server running in DMZ with dual NICs with F5 acting as reverse proxy. Wondering if someone could point us to where we need to go next for testing, troubleshooting to get this resolved.