Asuswrt-Merlin 378.56 returning to default usb modem settings

[zez1pp]

Hello everyone,

On my ASUS RT-AC66U I've faced an issue with usb modem settings. I can't save manual settings for apn, dial number, user, etc. Router each time comes back to location settings, ignoring my attempts to switch for "manual". I was searching forums for posts with identical problem, but have not found anything similar yet. Therefore, I'd appreciate if you can advise how it can be fixed (except hard reset and upgrading to the latest firmware). Maybe there is a way to customize default settings for ISP? I'd be grateful if you point me to any guidance!

 

[RMerlin]

Asus has made a lot of improvements over the years to their USB support. I would recommend trying again running a more up-to-date firmware.

 

[zez1pp]

more up-to-date firmware.

Yes, indeed I've tried last available (380.67) and it works perfect. I was able to change required APN settings. The only reason why I was staying with old firmware is, that usually on the latest one I get error "Your ISP's DHCP does not function properly". I was investigating possible reasons of this error and came to a conclusion, that it's related to IP, which is issued by my ISP:

ISP (cellular operator) is not assigning "real" public IPs, instead using of "private" one. There is no error on old firmwares (there are others ), but as soon as I update to the last available I constantly get this error message Your ISP's DHCP does not function properly". I was also trying to understand how it can be fixed...