After getting it all working I changed the default wi fi SSID and password as all the devices we have are set up to use the wi fi logon details we had on the previous router.
But in the last month the Hub 4 router has rebooted itself (on its own) 5 times and taken the router back to its default SSID and password.
At first of course we just think wi fi has gone down so switch the router on and off.
But when we then try to connect a device we find that our "new" SSID is NOT listed but the default SSID name IS listed.
I then have to logon to the router and change the SSID and password.