CPU requirements for iPhone tethering

Hardware Questions and Recommendations
1

Dear Experts,

Short version: what class of device is required to share a tethered iPhone's cellular connection, with a maximum speed of around 60 Mbits/sec, to a local network without being a significant bottleneck?

Long version:

I have connected an old iPhone by USB to a GL.iNet Mango to provide internet connectivity to my local network. It works but throughput seems to be constrained somewhere. Specifically:

  • A speed test (e.g. speedtest.net) from the iPhone itself gives a download speed of about 60 Mbits/sec.
  • If I connect the iPhone to my Mac using USB or a WiFi "personal hotspot", that also gets about 60 Mbits/sec.
  • If I connect the iPhone to the Mango, and then connect to the Mango either using its WiFi or via its ethernet, the speed drops to around 25-30 Mbits/sec.

My guess is that this is limited by the Mango's CPU, which is a MT7628NN (single core MIPS24KEc) @ 580MHz. But I could be wrong - I've asked a similar question on the GL.iNet forum, and someone has reported getting over 80 Mbits/sec with a tethered Android phone, hmmm.

So the question is: does anyone have any practical experience to share about what sort of device, i.e. broadly how fast / how many cores, or what specific device, would be sufficient to route between a USB-tethered iPhone and an ethernet LAN, at somewhere below 100 Mbits/sec? If you think that ought to be possible on a 580 Mhz MIPS, what should I do to investigate why I'm not getting that?

Many thanks in advance!

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3

What actual hardware speed is it on the router USB port?

I am impressed anyway you actually made the connection through USB, I tried just this on a edgerouter4 and a RaspberryPi with Ubuntu a couple of years ago and iOS was impossible to get to share internet to OpenWrt or a RaspberryPi over USB cable. Connect it to a laptop with actual operating system worked perfectly.
The only way that was possible to share internet hotspot to OpenWrt was through iPhones wifi.

4

Have you tried setting it up as a wifi hotspot instead of USB?

It will require some config job but If I remember right there is a wiki instruction for this operation.
But with wifi hotspot you doesn’t need to worry about drivers and compatibility issues.