If the uplink is wan, then in firewall you need guest->wan forwarding. lan masquerade is not needed.
If the uplink is lan, then you need to assign gateway and dns under lan interface.
Thanks @trendy, now it's working 
But unfortunately I can now connect from the guest network to my main network (e.g. 192.168.0.10).
Is there a possibility to restrict this?
If you look at my 2nd Screenshot, last rule was 'disable guest LAN'. That one does the job for me. Of course you need to adapt the ip address area..., ans maybe the target zone. I lost overview about your lan/wan zones.
Delete the guest->lan forwarding.
When I remove the forwarding the internet access does not work anymore.
Same here, I need to restrict the area 192.168.0.0/24 for my setup, but my main router has 192.168.0.1. I guess therefore the Internet does not work anymore when I apply that rule.
Have you set your main router as gateway in your lan and guest interface ?
Which one is your uplink?
After setting the router as gateway for the guest network it works with the Firewall rule. Thanks very much for your support
This topic was automatically closed 10 days after the last reply. New replies are no longer allowed.