The Pi appears to be configured properly. There are some problems with the SG-105E.
The trunk port (2) needs to be tagged in both active VLANs, and untagged in none.
Access (untagged) ports need to be untagged in only one VLAN, and their PVID (which is on a different page) set to the same VLAN number.
You can't delete VLAN 1 but you should move all ports out of it. Or use 1 as the number of the LAN VLAN (instead of 20)
Since the SG105E management interface listens on all VLANs, whenever there is more than one VLAN the SG105E must be configured to a static IP. Do not use the DHCP client feature. (If left active, the DHCP client would attempt to obtain an IP from your cable modem, and if successful it prevents the router from getting one).