To monitor the log in real time, first find the IP address of your PC. Eg 192.168.1.50
In a terminal on your Pi-hole run the following command, replacing this example IP address with that of your PC, in the same format with the backslashes. The character between the IP address and the word blocked is a vertical pipe symbol |
sudo tail -f /var/log/pihole/pihole.log | grep -E "(192\.168\.1\.50|blocked)"
That will show all the queries from your PC along with any responses which are blocked.
Then run the Discord app and see what is showing up. If you see any blocked entries which didn't first have a query from your PC then you can ignore it as it came from a different client on your network. You can whitelist any that look relevant that you've not already caught.
Here's the kind of correlation you're looking for, using a couple of random blocked domains here. Note these are unrelated to Discord, they're just examples from my log here.
Jun 28 12:53:52 dnsmasq[564]: query[A] segment-data-us-east.zqtk.net from 192.168.1.50
Jun 28 12:53:52 dnsmasq[564]: gravity blocked segment-data-us-east.zqtk.net is 0.0.0.0
Jun 28 12:53:52 dnsmasq[564]: query[A] js-sec.indexww.com from 192.168.1.50
Jun 28 12:53:52 dnsmasq[564]: gravity blocked js-sec.indexww.com is 0.0.0.0
Jun 28 12:53:52 dnsmasq[564]: query[A] cdn.cookielaw.org from 192.168.1.50
Jun 28 12:53:52 dnsmasq[564]: gravity blocked cdn.cookielaw.org is 0.0.0.0
Jun 28 12:53:52 dnsmasq[564]: query[A] media.cnn.com from 192.168.1.50
Jun 28 12:53:53 dnsmasq[564]: query[A] registry.api.cnn.io from 192.168.1.50
Jun 28 12:54:06 dnsmasq[564]: gravity blocked dit.whatsapp.net is 0.0.0.0
Jun 28 12:54:26 dnsmasq[564]: query[A] flightaware.com from 192.168.1.50
Jun 28 12:54:31 dnsmasq[564]: query[A] secure.gravatar.com from 192.168.1.50
Breaking these down...
Jun 28 12:53:52 dnsmasq[564]: query[A] segment-data-us-east.zqtk.net from 192.168.1.50
Jun 28 12:53:52 dnsmasq[564]: gravity blocked segment-data-us-east.zqtk.net is 0.0.0.0
... Query from PC which was blocked
... May be relevant and worth unblocking if this was Discord related
Jun 28 12:53:52 dnsmasq[564]: query[A] js-sec.indexww.com from 192.168.1.50
Jun 28 12:53:52 dnsmasq[564]: gravity blocked js-sec.indexww.com is 0.0.0.0
... Query from PC which was blocked
... May be relevant and worth unblocking if this was Discord related
Jun 28 12:53:52 dnsmasq[564]: query[A] cdn.cookielaw.org from 192.168.1.50
Jun 28 12:53:52 dnsmasq[564]: gravity blocked cdn.cookielaw.org is 0.0.0.0
... Query from PC which was blocked
... May be relevant and worth unblocking if this was Discord related
Jun 28 12:53:52 dnsmasq[564]: query[A] media.cnn.com from 192.168.1.50
Jun 28 12:53:53 dnsmasq[564]: query[A] registry.api.cnn.io from 192.168.1.50
... Queries from PC which were not blocked (no followup blocked entries for these domains)
... Not relevant since they were not blocked
Jun 28 12:54:06 dnsmasq[564]: gravity blocked dit.whatsapp.net is 0.0.0.0
... Blocked domain from another client (no preceeding 192.168.1.50 query entry for this domain)
... Not relevant since it was from another client
Jun 28 12:54:26 dnsmasq[564]: query[A] flightaware.com from 192.168.1.50
Jun 28 12:54:31 dnsmasq[564]: query[A] secure.gravatar.com from 192.168.1.50
... Queries from PC which were not blocked (no followup blocked entries for these domains)
... Not relevant since they were not blocked