Messages

If a machine wants to resolve an mDNS name, it sends a multicast message to port 5353. All the other machines see this message, and the ones that want to claim that name respond with a multicast message to port 5353.

What the relay does is simply listen to all these messages and for every message that comes in on one of the configured interfaces, repeat it on all of the other configured interfaces.

So with simple firewall rules you can't really distinguish between the requests and replies and what you want to achieve is not possible. You would have to use a different relay that allows you to be more selective. I don't know if that exists and if the results would be what you want.

The message "failed to reclaim memory" is sent by the operating system kernel if it runs out of memory and kills a process to avoid crashing the complete system.

I can see two reasons:

• The hardware or VM just has too little memory for what you're trying to do.
• You're loading a lot of large block lists which consume unexpectedly large amounts of memory.

So I suggest checking if the system has a reasonable amount of memory to work with, and if not, you either have to do less (less large blocklists, disable things that consume large amounts of memory) or increase the amount of available memory.