OpenWrt 18.06 Avahi/ mdns issues

After performing a sysupgrade on my TP-Link WDR4900 v1 from Chaos Chalmer to 18.06 I cannot identify or connect to any of my Apple printers or AirPlay devices in my house, even though they are connected to the router. I have tried a factory settings reset on the router and disabling ipv6, but no success.

Any idea what may be causing this sudden blockage and how to resolve this?

I know 18.06.1 is working great with regards to mDNS traffic, as I have a ton of Apple gear on my network.

I do run the mDNSresponder package on my router, but mostly so I can have friendly device names, and do things like ping laptopname.lan instead of looking up the current IP. Running on a C7.

In any case, here's how to troubleshoot mDNS:

To see all mDNS traffic flowing through router, you might need to first : opkg install tcpdump

This will send out put to stdout in text mode:

tcpdump -i any port 5353

To create a file that wireshark can open, use this:
tcpdump -i any port 5353 -s 0 -w /tmp/dump_any5353.pcap

Let that run for a period, then Ctrl-C.

To copy it to the current directory on the local machine (from terminal on the laptop):
scp root@ .

Also, you might want to do a simultaneous tcpdump on the laptop using a WiFi connection to the router to verify you are not losing mDNS packets (which are multicast) on the WiFi side of things.

Please let us know what the issue was,

  • Did you install any packages on the router to perform these functions?
  • If so, did you reinstall them after sysupgrade?

Thanks for the quick response! I had tcpdump run for a while and it came up with quite a lot of data. All is stored in this file:

I went through the details and did not notify anything out of the ordinary, except a lot of mention of ipv6 addresses, which I found odd. Any idea?

Nothing odd, it appears to be an Apple device doing some kind of discovery.

I'm reviewing the PCAP file in Wireshark, much easier.

Well, for some reason my wife's iPhone is able to pick up the AppleTV and a remote speaker, but the other devices don't pick up on it. Also, the Shairport-sync on the router itself is not identified anymore.

Resolved by going back to 15.05

Interesting, and exact same config on 15.05? Including packages?