Following the Troubleshooting guide, I have changed the MTU for bat0 interface to 1524. I'm getting this message in my syslog:
Jan 1 00:00:53 localhost kernel: [ 26.899762] batman_adv: bat0: The MTU of interface wlan0 is too small (1524) to handle the transport of batman-adv packets. Packets going over this interface will be fragmented on layer2 which could impact the performance. Setting the MTU to 1560 would solve the problem.
I'm not seeing any apparent performance issues, but do I really need to make the MTU 1560?