Hi,
at a first glance: Assigning two untagged VLANs (4,10) to the same "port" (SSID3(2.4G)), does not look like a correct configuration - hence use a different port (e.G. SSID4(2.4G)) for VLAN 10 (=GUEST2) and set PVID=10 for SSID4(2.4G). Same problem with two untagged VLANs (1,2) on the same port "LAN1" - VLAN 2 should be sent "tagged" (which corresponds to your DGS switch configuration for ports 4 ans 12 respectively). Your DGS switch ports look fine, except that tagged VLAN 10 (GUEST2) is missing for ports 4, 12 and 21. In your router a configuration for VLAN 10 has still to be done, given that VLAN 10 (aka GUEST2) shall have Internet access.
PT