I had wondered for a while that on Vodafone FibreX whether it's possible to have multiple addresses assigned over DHCP;
The modem supplied by vodafone contains two ethernet ports; it is possible to connect two routers to the modem and have two different addresses assigned. This normally requires a reboot of the modem.
The routers will have layer 2 reachability as the modem acts as a switch but may be assigned addresses in different subnets
Connecting the single modem to multiple routers is very handy in a shared flat because you can share an internet connection without having the security risk of sharing a LAN with your roomates.
The next experiment I tried was with my Ubiquiti EdgeRouter X, it had a switch0.10 interface assigning the router an IP. I then passed Vlan10 to one of the switch ports which connected to my Unifi AP. I was able to distribute my WAN over WiFi!
I think i tried maybe 3 or 4 addresses simultaneously, and it seemed to work. This was only an experiment and not a long term thing.
So far, for the past few weeks, I've been making use of the multi-gigabit port on the modem; one port is the huawei cpe for my family, the other is my own equipment and it seems to be working quite well.
Hope this was interesting/useful