Mesh problem

I have a Lyra mini mesh system at home but I have a regularly recurring problem.
I have 2 mesh nodes
Node 1: Master node
Node 2: Kitchen node

The PI (hass) is connected to the master node. My problem is as follows, when I am connected with my phone, computer, … to the master node, I can’t connect to the PI with the home assistant app, nor by the browser address. I receive a 404-message.

When I am in the kitchen with my pc or phone, or with nabu casa, I don’t have problems. Does someone know why?

Is there no possible way you can connect the pi via wired Ethernet to your router?

The pi is on wifi

Yes I got that. Hence my question:

Servers do not belong on wifi.