Windows 10 Stumped by network sharing problem

I've spent many hours trying to resolve this problem and desperately hoping someone can help - Please! My issue is that one of my laptops cannot access shared folders. The network uses a TPlink Archer C2300 router and I have a desktop PC running Win 7 connected to this by Ethernet. I also have a Lenovo W530 laptop and a Lenovo ThinkBook 15-IML which both connect to my network by wi-fi. The Archer router has a USB connection which has a SSD attached. The desktop and W530 are able to access and open the files on the SSD directly using file explorer/windows explorer from these. Nothing I’ve tried on the Thinkbook 15-IML allows access to this drive however although it appears in file explorer. In addition, although I can access shared folders on the Thinkbook 15-IML from both the desktop PC and the W530 I can’t access either device from the Thinkbook 15-IML because (although all devices show in file explorer) Windows reports a network error stating that it can’t access them. Both laptops are running Windows 10 Professional version 20H2 build 19042.867 and I’ve been through every setting I can think of to make sure they’re configured identically so I’m completely baffled as to why the Thinkbook 15-IML refuses to behave in the same way as the W530. I have, of course, made sure that the normal sharing and network discovery settings are correct and enabled SMBv1 to try and resolve the problem. Any ideas on what else I can try please?