Configuring more than one device with KNX integration

I have been trying to configure more than one device/configuration, but according to the integration only one device is to be configured, additional ones are not needed.

I have looked at some threads to see if there is any possible workaround, but all I could find was either to have some kind of router connected to multiple gateways, or have another instance of home assistant.

What I am trying to do is connect two KNX devices/gateways, each one is in another city, and I need to be able to configure those two devices in home assistant.

Is there any possible solution other than router?

The integration doesn’t support that. If you can’t combine these two to one ETS project and installation, I’d recommend to either use 2 HA instances or some Knx-Mqtt bridge.