For well over a year I've been using Seamless so my wireless mouse & keyboard work across my Win 10 Desktop PC and Win 10 Laptop PC. I would sometimes take the laptop away, and it would work seamlessly again as soon as I brought it back.

Now the behaviour has changed. When I bring the laptop back, it doesn't reconnect to be seamless.  If I go away for an hour or two, when I come back the seamless behaviour is working fine.  Likewise, if I put the Desktop and the Laptop to sleep overnight, they don't play together seamlessly when I wake them in the morning.  Again, if I leave them be for an hour or more I come back to find everything is working fine.

I noticed that on the Desktop there's a Multiplicity system tray icon which is greyed-out and which tells me Multiplicity is disconnected when I mouseover it. I can't figure out how to make it connect. The right-button restart of Multiplicity processes doesn't help. The corresponding icon in the Laptop's system tray at least looks live, and it shows the passcode that the Desktop copy is using.

I would be grateful for suggestions as to what's causing this problem, and what I can do to pre-empt it and remove the indeterminate delay.