L5 && DHCP server

When some other laptop tethers with the L5 through media USB-C (or BT), it normaly expects that the L5 assigns an IP addr to its interface usb0 and offers DHCP service on it, so the connecting device gets an IP addr on its own interface ue0 (FreeBSD) or en7 (MacOS), … incl. routing and DNS to be able to talk to Internet using the L5 (and its Wifi or data mobile connection) as a router (note: I say with intention router and not AP).

The L5 has no DHCP server (pkg isc-dhcp-server) installed or configured.

Why is this?

Your answer may be in this post :

That post was written back when things were a little different, specifically the shared connection method of NetworkManager was failing to set the required masquerade rule automatically so it had to be done manually. This is no longer the case and the behaviour desired by the OP can be done by simply chaning the method of the default NetworkManager connection from auto to shared.

However, the OP prefers ifconfig (net-tools) for managing the network on their phone and simple connection sharing as provided by NetworkManager is not available to net-tools.