Digi Connect ME by default will look for a DHCP server in network to get an IP address from.
In your case as you have connected directly to your PC/laptop Connect ME cannot find a DHCP server and it assigns auto ip to itself, which is 169.254.147.216.
And when you manually change all the octets, which is something like:
10.80.1.x or 192.168.2.x etc, you need to set the same range IP to your laptop/pc to make Device Discovery find the module.
This is not a limitation of Digi Connect ME , this is how it behaves. This is expected.
What you need to do is either connect Digi Connect ME and your laptop/pc to a network where DHCP server is available or assign static IPs both PC/laptop and Digi Connect ME.
Digi discovery uses ADDP protocol to find devices in network.
and it uses UDP broadcasts.
UDP broadcasts are usually blocked from one subnet to another and is the reason for device discovery not finding your device when it was set private IP and laptop/pc was assigned in another range.