Merlin,
I just started playing with a 3G/4G dongle (Vodafone K5150). I had Merlin 374.43 on my RTN-66U. I tried using the 3G as the only internet access, and also as a Dual WAN using the USB as the primary and ADSL as the secondary. I could not get the USB to connect to the 3G network at all (using Network Type: Auto//USB Adapter: Auto//all other settings default as provided by ISP). I tried the script mentioned on this thread, and it still would not work for me. I tried different Merlin Firmwares (39-43) and none of them worked.
Finally, I decided to try the latest ASUS firmware (374_5517). Using that firmware, and selecting USB (3G/4G dongle) as the only WAN access, it connects just fine.
Using the same ASUS firmware, and selecting Dual WAN with USB as primary and ADSL as secondary, the web GUI shows me connected to both USB and ADSL but I have no internet connectivity. So, it appears their implementation of the Dual WAN is not working properly.
After having it work with 374_5517 (single WAN, using USB), I decided to give 374.43 another try. No changes to other settings. Same result, no internet connectivity.
So, what are the differences between the ASUS USB implementation in 374_5517 and Merlin 374.43? Any recommendations or suggestions? Anything you would like me to try?
I rather use Merlin firmware and wonder if you could look into this issue.
Thank you very much,
MM