Wi-Fi 6 Mesh Wi-Fi - Next-gen Wi-Fi 6 AX1800

TP link router (main Deco unit) is connected to internet via port 1. Port 2 is connected to TPlink switch TL-SG108. Deco #2 is connected to same switch via ethernet cable. Deco #3 is connected to main unit via Wi-Fi. Both main and guest networks are active.

Main Desktop PC ethernet controller is connected to network and internet via the switch. Main PC ethernet can only connect via "Guest Network". Main network is either unavailable or invisible.

How can I remedy this problem?
Thanks