OK, funny. Currently it seems like clients connected via Wifi (directly to the router) can successfully reach servers, while clients connected via LAN or via Wifi on the access point (which is connected via LAN) cannot connect.
Ping and DNS queries (with both TCP and UDP) are working fine from all clients to all hosts I tried.
Any ideas where that might come from? Wifi connections not being tagged while LAN connections have a VLAN?
Kind Regards,
Johannes