Have the same issue here - or very similar at least.
Looks like my search skills not up to the job, as I found this thread after I posted this on my newbie thread.
I’d summarise my issue by saying - if the Android Remote & Bridge loses comms with the Core then the only way to re-establish the Remote comms to Core ( but not Bridge - this re-establishes fine ) is to reboot the Core - which takes quite a long time - timed it at 1 min 15 secs just now.
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Edit
Both Samsung phone and HD8 are connecting to Core straight away this evening - after Wifi disconnect & also reboot of device. Not sure what if any differences there are - flummoxed and slightly embarrassed here! Will try the combine zone test in the post below and update there shortly.