The change is that with the most recent version, we also try to get host names for devices in your network which are not actively using Pi-hole. Assuming your devices made only (or at least mostly) queries over IPv4 to your Pi-hole, we haven't tried to resolve their IPv6 host names before.
We're already looking into this. The issue itself comes from the growing number of temporary IPv6 addresses being enabled by default in Windows and Mac (if I recall correctly). My proposed solution is to add a new option REFRESH_HOSTNAMES which which you can change how the hourly PTR requests are made. I'm currently thinking about three options:
REFRESH_HOSTNAMES=NONE- Don't do any hourly PTR lookups
This means we look host names up exactly once (when we first see a client) and never again. This means we will miss future changes of host names.REFRESH_HOSTNAMES=IPV4- Do the hourly PTR lookups only for IPv4 addresses
This is planed to become the new default and should do away with the issue.REFRESH_HOSTNAMES=ALL- Do the hourly PTR lookups for all addresses
This is the same as what we're doing right now with FTL v5.3
This - including the new default IPV4 should resolve this issue. What do you all think? Any suggestions for improvement/additional options?