Bridge Mode with Cellular and why it’s not a thing

Bridge Mode vs. IP Passthrough on 5G Routers

Hey everyone — Alfredo here from Chester Tech Repairs. I get a ton of questions about bridge mode and IP Passthrough, especially when working with 5G modems like the Qualcomm. If you’re coming from cable or fiber, you might expect to just “bridge” your modem to use your own router — but cellular works a bit differently. Let me break it down for you.

What’s Bridge Mode?

Bridge mode is super common on cable or DSL gear. It basically disables all the routing features on the modem and passes the public IP address straight through to your own router. The modem turns into a dumb data pipe, and you handle everything else from your own firewall or router.

 

What’s IP Passthrough?

IP passthrough is sort of like bridge mode’s cousin. It still gives your router the public IP from your carrier, but the modem keeps its routing and management features active. That way, you can still log in to the modem for updates, band locking, signal checks, and all that good stuff.

 

Why You Can’t Really Use Bridge Mode on Cellular

 

With 5G (and LTE), true bridge mode isn’t supported. Here’s why:

✅ You need to reach the modem to change bands, run AT commands, tower lock, see signal strength, or upgrade firmware. If you fully bridge it, you’d lose that local access… Factory Reset City is the destination.

✅ The carriers often expect the modem to manage NAT and keep a data session (PDP context) open in a certain way. A true bridge can break how they expect your SIM to register.

✅ IP passthrough is a much better fit — it still hands your router the public IP, but keeps the modem reachable for you to monitor and troubleshoot.

What This Means for Your Chester Setup

 

If you’re using an SDX62, SDX65 or SDX75-based 5G setup, remember:

• Don’t look for a “pure” bridge mode — it’s just not there for good reasons.
• Use IP passthrough instead. You’ll get your public IP on your own router, but still be able to poke around inside the modem when you need to.
• Always make sure you leave a way to connect to the modem’s admin page or a management LAN, just in case you need to change something later. This is why Tailscale (a free tool) comes in handy.

If you need a hand setting up your 5G router, IP passthrough, or advanced things like carrier aggregation and band locking, feel free to reach out. I’m always happy to help get you the best 5G signal possible.