Using a tethered mobile phone as an Access Point

[Denigor777]

Hi,

Can an old Android phone be used as a USB-connected access point, rather than as a mobile-data hotspot?
Meaning:

ISP <-> Modem/Router (NAT/DNS/DCHP with USB and ethernet ports free) <-> ethernet to USB adaptor <-> Android Phone as hotspot <-> Wifi<-> Mobile devices

Using Android mobile as an internet connected router (Wifi hotspot or tethered) when it has mobile data is straight-forwards.
But using it as an access point, or even as an access point with routing (and even with NAT) to a tethered router... I haven't found a way so far.

And why? Because the world us full of old mobile phones which could be used as access points, WiFi repeaters, WiFi routers, NATs etc, if the software was developed for them. It just needs someone to create the software to do it... or compile open source WiFi router software to run on them. Someone far more clever than myself.

 

[Justinh]

I suppose it would be worth it only if your router didn't have Wi-Fi or else you have a 200' USB cable.

If your phone can connect to the Internet thru the USB cable, I'd expect your hotspot idea to work.

Try it and let us know.

 

[sfx2000]

I think the challenge with using an old handset as an AP is they were never designed for this purpose...

The WiFi radios are optimized for client usage

 

[Denigor777]

I think the challenge with using an old handset as an AP is they were never designed for this purpose...

The WiFi radios are optimized for client usage

The radio part of the hardware and software has been designed to be used as an access point. That's what it is when it's setup as a hotspot. That bit is not the problem.

The ability to NAT and be a DHCP server is already there too (router functions, not AP functions). Also Mobile hotspot uses this.

Routing IP to/from the LAN interface (USB or ethernet via adapter) is also there. Used when setup as a tethered router.

There are 3 interfaces capable of Layer 3 (LAN via USB, 4G/5G radio, Wifi). All are routable. We can have LAN and AP working at the same time too (mobile hotspot and USB/ethernet tethering)

The only missing part appears to be enablement of routing between AP and LAN... radio etc is all there and proven already.

 

[Denigor777]

The radio isn't the problem, it can handle multiple wifi connections fine. Routing from Android via the USB port is 'reverse tethering'. Here's one solution I found: https://www.smartprix.com/bytes/how-to-reverse-tether-pc-internet-with-android-phone/

But that requires software on the gateway side. And I don't yet know if it will work with mobile hotspot on the Android (I doubt it).

 

[flyboynm]

Hi,

Can an old Android phone be used as a USB-connected access point, rather than as a mobile-data hotspot?
Meaning:

ISP <-> Modem/Router (NAT/DNS/DCHP with USB and ethernet ports free) <-> ethernet to USB adaptor <-> Android Phone as hotspot <-> Wifi<-> Mobile devices

Using Android mobile as an internet connected router (Wifi hotspot or tethered) when it has mobile data is straight-forwards.
But using it as an access point, or even as an access point with routing (and even with NAT) to a tethered router... I haven't found a way so far.

And why? Because the world us full of old mobile phones which could be used as access points, WiFi repeaters, WiFi routers, NATs etc, if the software was developed for them. It just needs someone to create the software to do it... or compile open source WiFi router software to run on them. Someone far more clever than myself.

Some routers allow you to tether your cell phone to them directly - Asus and Synology are 2 that I know of that have that capability. They DO have requirements on the age of the cell phone though. I would go to their websites and look up cell phone tethering to their routers. I used my Samsung A54 cell phone tethered to my Synology RT6600ax a few months back when the Internet was out in my neighborhood for a few hours.

 

[Denigor777]

Some routers allow you to tether your cell phone to them directly - Asus and Synology are 2 that I know of that have that capability. They DO have requirements on the age of the cell phone though. I would go to their websites and look up cell phone tethering to their routers. I used my Samsung A54 cell phone tethered to my Synology RT6600ax a few months back when the Internet was out in my neighborhood for a few hours.

You may have misunderstood the thread. You describe tethering, and we know that works fine. This thread is discussing reverse tethering, where the phone uses the PC for Internet access (and the phone wifi as hotspot AP)

 

[sfx2000]

The radio part of the hardware and software has been designed to be used as an access point. That's what it is when it's setup as a hotspot. That bit is not the problem.

The primary purpose of that WiFi radio is to be a client - it's not intended to be used 100 percent of the time as an AP...

More importantly, because it's a mobile phone, power management does become an issue...

The ability to NAT and be a DHCP server is already there too (router functions, not AP functions). Also Mobile hotspot uses this.

Agreed - this happens with both Android and iOS - nothing new here...

Routing IP to/from the LAN interface (USB or ethernet via adapter) is also there. Used when setup as a tethered router.

Maybe on some Androids - not on all of them, and not on iOS...

There are 3 interfaces capable of Layer 3 (LAN via USB, 4G/5G radio, Wifi). All are routable. We can have LAN and AP working at the same time too (mobile hotspot and USB/ethernet tethering)

The only missing part appears to be enablement of routing between AP and LAN... radio etc is all there and proven already.

All true - just that Android is not optimized for this task...

 

[flyboynm]

You may have misunderstood the thread. You describe tethering, and we know that works fine. This thread is discussing reverse tethering, where the phone uses the PC for Internet access (and the phone wifi as hotspot AP)

Yeah, I got it backwards. Sorry.