Question about scheduled 3G connection[solved]

[xxcmax]

Hi All!
My router is AC68U. Now it working with a 3G USB modem well, the 3G package is 300 hours per month so I need the router connect 3G follow a schedule (eg. connect at 8:00am and disconnect at 6:00pm every workday). I think it can be done by using the cru and nvram command, first I should try to control 3G connection through modify nvram settings. I enabled the USB Modem switch at WEB UI and save all contents of the output of "nvram show" into a text file, then do that again after disabled the switch. I compared two output files and found several settings which may controls 3G connection.

USB Modem enabled:
usb_modem_act_int=ttyUSB0
nvram set svc_ready=1
nvram set link_wan=1

USB Modem disabled:
no usb_modem_act_int param in the output of "nvram show"
nvram set svc_ready=0
nvram set link_wan=0

I tried modify those settings by "nvram set" "nvram commit" and confirmed by "nvram get" before reboot, but all the settings I modified recovered after a reboot. I tried to "nvram save/restore" the two states of USB Modem switch and it works, successful controled the 3G connection. But "nvram restore" will remove all files in the jffs partition include the most important "services-start" script. Now I don't know how to do the next. Is there some way to implement a scheduled 3G connection?

Thanks for all your advise!
And sorry for my poor English.

 

[xxcmax]

Problem solved. I made a foolish mistake, I accessed the router through SecureCRT. After "nvram show", I right clicked the window and choose selectall->copy->paste to notepad. But what I did couldn't save all content of nvram settings for there are too much settings to display in the window, the first half of the output was removed. After found this mistake I tried "nvram show > 1.txt" and got all of nvram settings. It is weired that jffs format was set to 1, all files in jffs partition was removed after "nvram restore" was because of this. I set jffs format to 0 and then tried to restore nvram, files in jffs was reserved after reboot. Now the scheduled 3G connection is working well.
Sorry for wasted your time.