Bonjour / mDNS / DNS-SD Problems - Can't find Time Machine server on local network. Disappeared.

[rramalho]

Hi all,

I'm having a real and wierd problem on my macOS machine (2012 Mac Mini, 16Gb RAM, latest Catalina). My QNAP Nas suddenly desappeared from my time machine backups. I started digging and found that everything is fine on the NAS. I also can't find my HP Printer via Bonjour, but my iPhone can.

It seems that my mac can't find most services on the network via Bonjour/mDNS. My network is setup via DHCP, and I have IPv6 enabled (Link-local).

Using the program Discovery I can find some services, but not all.

Using the same program on iOS I can find all the programs/hosts on the network. Same network setup.

I've already tried to reset the dns cache using:

sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder

That did nothing.
Using the dns-sd terminal program I get similar results.

Can anyone point me on the right direction, so that I can see all my network's services on this mac?

Thank you!

 

[Halifax126]

I had a problem that sounds similar but with an older Synology server. Couldn't access the shared folders though the finder unless did a "Command K" server link. When I did this "afp" and "smb" worked perfectly and the drive mounts on the desktop.

I couldn't find a solution on line. I ran the 10.15.4 ComboUpdate to see if that would fix it. It worked once and everything was back to normal but then failed when I tried to reaccess the server a second time.

I then tried OnyX and ran all the scripts and the "Maintenance" action (including rebuilding the indices and checking the file system). I then rebooted the system and everything was back to normal - perfect access to the server!

That is my story - very much "a throw stuff at the wall and see what sticks" approach; I don't know why it worked. Your milage may vary

UPDATE - Spoke too soon. The problem came back. Sorry I couldn't help. I thought I had a solution.