Cant access lan side clients through wan port with 2 routers

Hello,

I want to achieve this:

Have access from right side router clients, for example 192.168.10.21 to access specific left side LAN IPs, for example 192.168.100.101.

The left side Opal router is in normal router mode, with WAN set to IP: 192.168.10.2 gw: 192.168.10.1

The right side other router is a 4g router. Internet works fine.

I want to get access though from right side clients, wifi in this case connected to the wifi of right side router, to access specific lan side clients on the left router and I cant get it to work.

I have tried so far:

Left side in Luci set WAN to accept accept accept:

image

And also set a static route on the right side for:

192.168.100.0/255.255.255.255 via 192.168.10.2 unicast

This doesnt work though and I dont know why.

Anyone have an idea what I do wrong or what is missing missing?

I have tried enable “drop-in gateway” on the left side Opal router and disable DHCP server on the right router. Still not working. I then changed WAN in LUCI to this:

Allow forward to destination zones:

image

and now it it is working. Not really sure why though. Also this seems to be a design flaw with drop-in gateway. If you enable drop-in gateway all flow including forward should be allowed on the WAN port. Either Glinet changes this, or put another option into the drop-in gateway interface page, where you enable “allow all forward from wan”.