After designating the DHCP server settings on my linksys router to point to Pi-hole on local network as DNS, Linksys router should designate the Pi-hole as the default dns server for all local clients.
If you can provide us with a debug token, I'll take a look and see if I can spot something.
To that end, please upload a debug log and post just the token URL that is generated after the log is uploaded by running the following command from the Pi-hole host terminal: