Can a router use USB modem connected to Raspberry?

[Pila]

I have problems with Asus Meriln routing on ocassions. Got no help in resolving issues. So, my only possibility is to restart a USB modem to make it reconnect. Got no help with that, too.

Restarting entire router is not a nice solution in some situations. But, currently it is my only option. I do it for months now. Every 1-2-3 days, never mor than 5 days. We are talking remote access and 24/7 automatic function. So, pulling the USB modem out of the USB and putting it back is not a solution.

I have 3 solutions to separatelly restart USB modem without restarting a router. Only one is completely free and with no cable clutter at all:

Connect USB 3G modem to a Raspberry Pi (LibreElec). This is likely posible. RPi is plugged via LAN to the router. And if a USB modem needs rebooting, handle it with Raspberry. Reboot the router only if needed.

Router must remain the boss in the network (DHCP, DDNS, VPN...). Everybody gets the Internet access via the router.

Can I do it? How? Make my Raspberry Pi the gateway in the router?

Routers are Asuswrt-Merlin RT-AC56U_380.59_0 and AC68U.

 

[sfx2000]

The concern is that the Pi likely doesn't have the throughput that would be good for a solution like you're thinking about - the onboard ethernet port isn't very fast, even for 100BaseT... and this goes for both the Pi2 and Pi3...

Raspbian is a full on linux distro, so it is possible... but this is more of while one could, one shouldn't... I would continue to try and get that modem working with the AsusWRT on the router...

 

[Pila]

Same problems exist with another USB modem which is 4G Double NAT (this one is 3G single NAT). Speed is not an issue, 10 mbps is too much.

Thing with a Raspberry seems a bit complex But, I just got another idea about killing the power to the USB modem So, I will do that thing to reset the modem.

Problem is that reseting the modem sometims creates new set of priblems with the router (it stops routing to the outside).