Why does 3G configuration disappear after AR1220-S update from V2R1 to V2R2?
AR1220-S version before update: V200R001C01
There is default USB 3G interface in the configuration:
2 interface in system default configuration disappeared after updating to v200r002c00spc100.
Because the difference of versions, v200r002 version 3G interface is not built by default.it will built only when 3G data card was inserted.
So it is normal that 3G interface configuration disappear after AR1220-S update.
3G interface correspond USB location outside on AR1220. You can ask for users whether they insert the wrong interface when occuring the problem.