Further info - when I plug in the USB lead from the hub (and hence AstroEQ and DSLR) to the laptop, and look at properties of the USB Serial Port via Device Manager, under the events tab, it installs the Windows usbser.sys driver which has a result code 0, and then attempts to load the AstroEQ driver mchpcdc.inf, which fails with error code 0x0. So that'll be why its not working then....but why has that suddenly started happening? It happens exactly the same whether I plug the AstroEQ directly into the laptop or via the USB hub, so the hub is not a factor. At least I know where to look now...
Edit - and when I said above that AstroEQ config could talk to AstroEQ, it looked like it was - but actually it can't....
Edit 2. I found the link on this site which says that I don't need the AstroEQ driver under Windows 10, because the one supplied with Windows 10 (usbser.sys) works fine by itself. I also think I know why the system is trying to load the AstroEQ driver - it is because the property "included infs" for the USB Serial Port is set to "mdmcpc.inf", i.e. the inf for the AstroEQ driver. What I am currently trying to find out (with little success, despite much googling) is how and where "included infs" might be set, and more specifically, how to unset it!
Edit 3. After last update, Tom came up with the news about issues caused by EQMOD v2.00. As I have EQMOD 2.00K you can guess the rest. Downloaded new config utility, allowed me to connect to AstroEQ, installed new firmware, detected and fixed corrupt EEPROM, re-entered my config, and laptop and AstroEQ now seem best friends again. Now to load up the mount, connect everything in live configuration, and make it sure normal service has been restored. Tom, thanks very much for detecting and fixing this so quickly.
Paul