A bit more info for anyone else who wants to try to get this working (which I have at long last!).
1. Although I had shared folder on both machines (I was trying to do this both ways, between two Win10 clients with HomeGroup) to 'everyone' 'full access', it seems as though HomeGroup has its own way of doing things!
2. Using VEB one machine COULD browse the network to see the other, but not the other way round (OK that might be down to something wrong on my PCs).
3. On the one which couldn't browse, I typed in the path to the other folder \\PCname\folderpath\ AND also said that it needed credentials (even though everyone had permissions!)
4. In order to give credentials, I had to create a user which was recognised by the other machine.
5. Homegroup, or this aspect of it, doesn't like blank passwords! Since we are all the same family, almost everything within the house is NOT password protected, but this user had to have a password.
6. Everything then seemed to start to work, but failed. Application log revealed CAPI event 513 which is a strange, but known, problem with incorrect permissions on a particular MS folder, and is also something to do with VSS which I guess VEB uses . . . I Googled and found a script and ran it (crossing my fingers!) which sorted that out.
So it's all working now . . . . and I suppose was worth the effort (as I enjoy problem solving, and don't like to be beaten by a mere machine, or Microsoft!).
Good luck if you want to try the same.
Computer Manager at Bedford School, UK (since 1999).
Veeam user since 2009.