i am trying to do a "router" from Raspberry Pi 4 2GB Model. Rpi all is set, working, installed updates etc.
Pi will run standard Raspbian Bullseye (newest OS), with Pihole and other software. I cannot run other OS, since i use it for more things (running Grafana, Influxdb, Nodered, Python scripts etc etc...)
My idea is - Connect a mobile phone to Rpi, share internet via USB tether to LAN port. There is a network switch (dumb one), which connects all other network devices together. Since Pihole has its own DHCP server, i thought i could omit router from network, as currently it assigns all DHCP stuff. I KNOW i cannot run two DHCP servers at same time, if i unconnect router from LAN, whole network will fail to communicate = DHCP on Pihole is not working.
Internet does not work on PI itself (i cannot even apt update it, since it obviously looks for update servers on LAN network, which there is none, since it is blind network). It does work however when i unconnect the LAN cable.
My current router does not have USB, and buying one is a bit overkill.
Is this doable? Am i missing something? I think i need to bridge connection - USB0 - ETH0, but i am bit lost since there is very little about such use case on internet...