Hi Steve,
It sounds like the other box still has a fixed internal IP number, so it probably just needs
to be changed to DHCP.
In either case, just use the Microbit Setup Manager via USB. This allows you to change to DHCP,
call-up the IP address and have the browser go directly to the box. It looks like you already are
using the Setup Manager, so just make sure that DHCP is turned on.
73,
Mitch DJ0QN / K7DX