Low Speed of USB 4G dongle on AC68U

[Offler2]

Been testing 4G usb modem DWM-222.

Failover/fallback works fine, and its even possible to send SMS notifications from the console.

However Speed test shows 40mbit download and up to 8mbit upload when used over router. (Measured with pc over ethernet).

Modem is 4g LTE Cat4 which means its capable up to 150mbit download and 50mbit upload.

When connected to a windows PC via USB 3.0, speed test shows download and upload very close to this spec.

I tried both ports 2.0 and 3.0, with powered hub.

Cpu nor Ram are hitting any limit, usb also does not seem to be the limiting factor.

Router Firmware is stock, Dual Wan, configured as failover with fallback. No customizations...

Modem indicates 4G network (green led, blinking)

Even when 40/8 mbit is enough as a backup, at least 100mbit would allow me to work/watch without any limits. Also connecting it directly to pc isnt a solution - i have to share the network with other devices.

Router is otherwise capable of 930mbit over ethernet wan.

Where to look to resolve it? Is there a way?

I suspect there is double NAT going on or CTF disables for some reason.

Will try Spoof TTL value later today.

 

[Crimliar]

Our routers tend to have pretty feeble CPUs. When they're being used in the normal manner, there is a great deal of hardware assistance taking place. When you start using a mobile dongle, I suspect that the CPU needs to be doing a great deal more work than normal, and just can't keep up. *Very willing to be proven wrong on this, you will probably be able to tell by looking at the CPU usage in the routers Web UI!

 

[sfx2000]

Keep in mind that 4G modems have packet overhead due to PPP - so if the default MTU is 1500, things will get fragmented and performance will suffer.

Drop MaxMTU down to 1420 and work it up from there...