We ask that you post the debug token only. This keeps your debug log private - only the Pi-hole team can access the log at the URL you provide and it auto-expires in 48 hours.
Your DHCP server is passing out the IP of itself for DNS, rather than the Pi-hole IP:
*** [ DIAGNOSING ]: Discovering active DHCP servers (takes 10 seconds)
Scanning all your interfaces for DHCP servers
Timeout: 10 seconds
* Received 356 bytes from eth0:192.168.2.1
Offered IP address: 192.168.2.197
Server IP address: N/A
Relay-agent IP address: N/A
BOOTP server: Speedport-Pro-Plus/120141.5.0.018.1
BOOTP file: (empty)
DHCP options:
Message type: DHCPOFFER (2)
server-identifier: 192.168.2.1
lease-time: 1814400 ( 21d )
netmask: 255.255.255.0
router: 192.168.2.1
dns-server: 192.168.2.1
renewal-time: 907200 ( 10d 12h )
rebinding-time: 1587600 ( 18d 9h )
broadcast: 192.168.2.255
domain-name: "speedport.ip"
--- end of options ---
DHCP packets received on interface lo: 0
DHCP packets received on interface eth0: 1
Your P-hole is configured at a different IP:
*** [ DIAGNOSING ]: Name resolution (IPv4) using a random blocked domain and a known ad-serving domain
[✓] info.my-chatprogram.xyz is 0.0.0.0 on lo (127.0.0.1)
[✓] info.my-chatprogram.xyz is 0.0.0.0 on eth0 (192.168.2.197)
[✗] Failed to resolve doubleclick.com via a remote, public DNS server (8.8.8.8)
From a client that you believe should be connected to the Pi-Hole for DNS (the PC in this case), from the command prompt or terminal on that client (and not via ssh or Putty to the Pi), what is the output of
nslookup pi.hole
nslookup flurry.com
Are you running any firewall software that would be blocking port 53 traffic? Something is preventing the Pi from connecting to the Google DNS server and to our nameserver:
*** [ DIAGNOSING ]: Operating system
[i] dig return code: 10
[i] dig response: dig: couldn't get address for 'ns1.pi-hole.net': failure
The Pi nameserver is also set to the router IP. I recommend that you change this to any public DNS like Cloudflare, Quad9, Google, etc. This allows the device to continue to reach the internet in the case of a problem like you are having now.