I couldn’t give you the correct answer before I knew if NAT would be enabled or not.
Given it is enabled you will need to do the port-forwarding section: Firewall - GL.iNet Docs
You can only route 1 external port once. So if you have a devices 192.168.2.2 and 192.168.2.3 both needing port 80, you can only have 1 of them on external port 80.
The port forwarding for this could be:
Rule #1:
Internal IP: 192.168.2.2
External Ports: 80
Internal Ports: 80
Rule #2:
Internal IP: 192.168.2.3
External Ports: 81
Internal Ports: 80
This way 192.168.2.2:80 is reachable on 192.168.1.X:80 and 192.168.2.3:80 is reachable on 192.168.1.X:81 (X being the IP given to the GL Inet). Same would apply to port 22. You gotta pick another port and remap it to 22.
The restricting of access can only be done under the “advanced GUI”: More Settings - GL.iNet Docs
In the advanced GUI under Network → Firewall → Tab “Traffic rules” you can setup rules which block all traffic except traffic coming from the allowed IPs. Be careful with the firewall rules, you can block more than you might want! The order of the rules is important! Allow then block, not block and never reach allow.