Can't find Core from remote normally, but found instantly after toggling "Accept Remotes"

I have had problems with Roon Remote connection which I was emailed about but due to a bereavement was unable to follow up on.
Last night the problem returned and I have finally found a solution.
Windows 10 laptop as core, android remotes.
It initially connected then lost connection. I restarted the Tablet. Re started the core and the problem remained.
This morning, still no connection so I went to settings and turned ‘Accept Remotes’ of and on again. Voila! My remote connected immediately.
Just my experiance , Chris

the Remote, when looking for Cores, will say to everyone on the network ‘Cores, where are you?’

the Core, at startup or (turning on of 'accept remotes"), will say ‘I am a Core here’ to everyone. It will also say it on reception of the above question to the Remote that asked.

If toggling the ‘Accept Remotes’ fixes it, it means the Core can send the discovery packet to the remote, but the remote can’t seem to ask for it. This sounds like network badness – firewalls blocking packets is a good guess to what is wrong.