Thanks James. So clear and so quick to implement. Now all working fine. I did initially have some difficultly with the sudo rip-update. Got !!!failed messages about ca-certificates and time not being set correctly. Unplugged everything. Plugged it all back in again. Tried again and it worked.
I have seen a James Chambers tutorial on booting the 4B4 from the usb drives. I am going to follow this and see if I can get Rachel running this way. I hope the benefit would be c. 300 MBS upload speeds?