Even though I'm late to the party, I ran into the same issue yesterday and solved it by
1. nslookup pgk.opnsense.org from another machine
2. on opnsense I added the entry (ip + url) via vi to /etc/hosts
3. From Web UI pressed the update button -> bind updates were available
4. installed the updates and rebooted
5. everything worked again
1. nslookup pgk.opnsense.org from another machine
2. on opnsense I added the entry (ip + url) via vi to /etc/hosts
3. From Web UI pressed the update button -> bind updates were available
4. installed the updates and rebooted
5. everything worked again
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