WLAN to LAN connection fails

[mcnesium]

I run a Realsoft APU.4D4 Firewall/Router with wifi module that came with preconfigured OPNsense firmware. Today it runs OPNsense v22.1.3. It has four network ports, `igb0` is configured as WAN, `igb1` was a DMZ, and `igb2` and `igb3` regular LAN interfaces.

The DMZ configuration came inconvenient to me, because I want to run a homeserver on it, that serves as webserver (Nextcloud etc) as well as mailserver and tons of other stuff where it needs to connect to the internet by itself. So I decided to ditch the DMZ configuration and created an all-asterisk firewall rule for the DMZ interface in analogy to the "Default allow LAN to any rule" that was pre-configured to the other LAN interfaces.

This gave the Nextcloud server connected to the DMZ interface access to the internet, so that worked. Also devices connected to the other LAN interfaces are able to connect to the Nextcloud and so on. So far so good.

Only devices that are connected to the router via the wifi network (WLAN interface) are unable to connect to the Nextcloud server, that is connected on the DMZ interface. Though: wifi devices are connecting fine to devices that are also in the Wifi network themselves (rpi/kodi) or the LAN interfaces (rpi/homeassistant).

This raises the assumption that there is some other setting hidden somewhere, that prevents wifi devices from connecting to the old DMZ interface. I have tried to contact the customer support of the seller, but unfortunately they closed down due to covid-foo.

Dear forum, could you please give me some hints on what I should look after to make the DMZ a regular LAN port?