MR5100 - USB Connection Speed issue – RMNET Driver & Slow RNDIS Speeds on Linux Machines

[pingumon]

I've been struggling to achieve high-speed USB tethering via RNDIS on Linux-based systems. Previously, I had good results using an OpenWrt setup with the CDC-Ether driver, but even that is now affected by the same slowdown. At this point, I'm uncertain whether the issue lies with the MR5100 hotspot itself or if recent changes to the Linux kernel across different distributions are to blame.

For instance, I used to get speeds around 800 Mbps on Ubuntu, but now I max out at about 70 Mbps. Meanwhile, connecting the same MR5100 to a Windows machine yields speeds of up to 1.2 Gbps. This discrepancy has been puzzling me for quite some time.

Interestingly, I also own the MR1100 model, and when I use the same SIM card in it, I consistently get high speeds on both Linux and Windows machines. This makes me suspect that the MR5100 might somehow be detecting the host operating system and throttling the USB tethering speed on Linux.

Another related issue is the slow IP Passthrough performance when using the MR5100, regardless of whether I'm connecting via USB or Ethernet. Again, the MR1100 doesn’t suffer from this problem.

So, I have two main questions and would appreciate any insights:
Why is RNDIS speed significantly slower on Linux distributions?

If there’s no workaround to fix RNDIS performance, does anyone know how to use the RMNET driver with these Netgear hotspots?

Any advice or experience shared would be greatly appreciated!