[GraemeJ]

Wow, that's really bad news Graeme.  Can you check if there is a way to unblock/forward ports in the router? The ports used by the companion app are 8888, 16568, and 16569.  I'm assuming you don't have any firewall software running on your PC and you've ensured that Windows Firewall isn't blocking the companion.  Getting a new router means all of the IP addresses probably changed, and this could have potentially changed something in software on your PC.

I've also tried viewing about 15 different backup files in the companion app, and they have all worked. I'm really not sure what to do at this point unless someone can provide a backup file that no longer works.

Mike

1 - Bad news indeed.  I'll have to delve into the new router's software and see if any ports are being blocked (which will be fun, as it's in Spanish).  Actually, I'm not that happy with its performance anyway, it's supposed to be 'high power' but performs no better than the €20 router it replaced, so I'm talking with the manufacturers about that.  In the meantime, I might well be putting the old one back temporarily.

2 - Windows Direwall is turned off - in fact, I can't even turn it on, never worked out why that should be - and I'm running Webroot on both the PC and the tablets.

3 - I have several backups that I can't extract, but I am certain there is nothing wrong with any of them (except, perhaps, the last couple, which I obviously have been unable to check).  They have all worked in the past.  I know this because I often use the feature to produce a printed chart for someone.  Whatever the problem is, it lies elsewhere.

For the moment, I have made backups on the tablets, just in case of a problem.  However, I'll only use those in a dire emergency, as I have no way of knowing if they will actually work without trying them out and if they fall over, then I have nothing!!