Tailscale on GL.iNet Slate AX only works with upnp


I would like to setup tailscale with subnet on my router. I got it working but with upnp. It mentions on the openwrt documentation it is not recommended and secure. I can ping my phone from the router in ssh with taiscale ping. But not the other way around.

I am aware that this is probably not enough info to know where the problem is exactly but i dont know much more of netwoking. Any help woud be appreciated.

Thanks in advance Jens