Mainly while checking out the syslog utility, I noticed that every 5 minutes I'm getting a message

[ARP][Arp address mismatch - Ethernet destination address doesn't match ARP target address]

I doubt anyone is trying to spoof devices on my network, but is there any way to to get more information such as the MAC or IP addrs this relates to?

Thanks.

Just wondering, would Android's MAC address randomisation look like a periodic mismatch to the router?

The MAC randomisation shouldn't be visible to the router / wireless networks in that way because that could mean its providing its real MAC at some point in its connection.

I think there should be some more details to what the ARP mismatch could be. But if it's breaking things, you can turn the ARP checking off from [Firewall] > [Defense Setup] > Spoofing Defense.

No it's not breaking anything, just a minor annoyance that could instead be providing useful information

Is this pertinent, at all?

https://www.draytek.co.uk/support/guides/kb-arp-address-mismatch