Then, if I understood correctly, your original title is wrong... the dashboard is working, but the graphics are empty.
Your attempts to "fix" PHP didn't help because there was no PHP issue.
Your database contains data:
*** [ DIAGNOSING ]: Pi-hole FTL Query Database
-rw-rw-r-- 1 pihole pihole 1.9G Jan 31 11:08 /etc/pihole/pihole-FTL.db
but I'm not sure if your devices are currently using Pi-hole.
Pi-hole is working, but your router is not advertising Pi-hole as DNS server:
dns-server: 192.168.1.1
router: 192.168.1.1
Are you sure your devices are using Pi-hole?