You can try swapping the 2 output cables.

A modem modulates/demodulates. A router routes

Most modems these days are combined with a router. So yeah you can use the routing capabilities and plug into a smart/dumb switch and it will work

https://store.amplifi.com/products/amplifi-hd-mesh-router

I get great range and the lcd screen makes updates and troubleshooting very easy. My parents and a few friends use this and it is rock solid.

Costco.com has series 9 $60 off at $329. Think that is your best bet

I have an extra “hyper m.2 x16 card v2” if you want it

Check bios for lower fan profile.

Can also add a pci slot fan or whatever additional fan you can fit. Idea is extra fan keeps idle temp lower so loud fans don’t spin up as often

Just close the door.

I once bound a /16 to a server. Dropped like a rock instantly over ssh attacks 😂 over 10,000/s