Setting up Phone As HOME ISP

You can use your phone for home internet if your regular provide (DSL, Cable, Fiber, Sat, etc.) is down

While it is fairly easy to turn on the mobile hotspot in your phone and share its internet service with other wireless devices on your home network, it is not so easy to share that service to wired (ethernet) devices on your home network. Here's how I use an android mobile as backup internet service for my home network without need to make ANY network configuration changes.

First, why? Typically we have two or three long power outages every year (where we lose power for more than 24 hours). Our DSL lasts for just about 20 hours, hence we lose internet durng those longer outages. Sometimes the power and internet can be out for 3 or 4 days.  Of course our individual mobile phones continue to function because most towers have diesel backup.

In these extended power outages my home automation, and other internet-dependent systems stop working. Yes, it's really just a first world problem but I like to hack around so I came up with a solution that allows me to switch my entire house over to my phone's internet with NO network configuration changes (once setup).  

How?

1. First off, I've been using an OpenWRT router between my home network and the DSL company's router for years to allow me to do some traffic shaping and to insulate my network if I change my ISP.

2. Many off the shelf routers can run the OpenWRT firmware (free). I use an older TP-Link wireless router that I got on ebay for $20 and it works great.

3. OpenWRT has an optional "load balancing" module that I installed.  It is based on the "MWAN" linux package.

4. My Samsung android phone, and my provider, Visible, support "USB tethering".  Using USB Tethering is preferable to using the phone's mobile wifi hotspot because the USB is faster and uses less power, allowing the phone to be charged by the router's USB port. Setting up USB Tethering requires a few one-time changes in the phone's settings and then when I want to use it, it is turned on from the Settings/Connection menu.

5. In the router, the load balancing module is setup to prefer my ISP's DSL service if available but automatically detects when it goes down and then switches all traffic to use the phone that is plugged into the router's USB port.

6. That's it. If my DSL service goes down, I just plug the phone into the router, turn on USB Tethering in the phone and the rest is automatic.  The speed is quite respectable as well and the UPLOAD speed is 5x better than my DSL. 

7. Hmm... maybe I should just use a phone for the house's regular connection?  Unfortunately, the USB tethering is capped at 10mbs down and up. But my regular DSL is only 17mbs down and only 1.5mbs up, at more than twice the monthly cost!

8. Why not get a better home ISP?

   1. Fiber will probably never come down my road.

   2. Cable company wants $10,000 to come down my road.

   3. Starlink is unreliable for meetings and streaming here and costs $125/mo!  It also stops working during thunderstorms.