OpenWrt 18.06 Avahi/ mdns issues

Installing and Using OpenWrt Network and Wireless Configuration
1

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?

2

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@192.168.1.1:/tmp/dump_any5353.pcap .

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,

3
  • Did you install any packages on the router to perform these functions?
  • If so, did you reinstall them after sysupgrade?
4

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: https://drive.google.com/file/d/1qi50CXraL3RM2v9yotul2Zc_4M47Oq6G/view?usp=sharing

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?

5

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

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

6

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.

7

Resolved by going back to 15.05

8

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