If you intend to use your BPi-M5 as a data centre for your home (e.g. talk to a load of sensors/arduinos) then your Pi will need a static IP address (one that never changes) on your network.
Log into your Pi as superuser (su) as normal... and type
This opens a configuration window. Scroll down to: Network and press enter to activate OK
Next screen: choose IP and press enter to activate
Next screen: right scrool to Static and press enter to activate
Next screen: fill in ALL the boxes, as in this example
Once done, press OK
Reboot and reconnect using the new IP address