Saying that it didn't work doesn't say much. What didn't work? Did it get an IP address from the Router? Did you setup a Static IP address on the OBi110 before taking it to Vietnam? If you did, your Router in Vietnam might be on a totally different IP range (subnet?). For instance if you assign a Static IP such as 192.168.1.50, but the Router is set up to hand out IP under 192.168.2. xxx, the OBi110 will not get an IP from the Router. Can your wife try plugging the OBi110 into another Router at another location?
If you need help, you need to provide more detail information beyond that it did not work. What lights came on when the OBi110 was plugged into the LAN Port of the Router. Do you know the Model number of the Router, etc. Could she dial the Obihai's echo test number: **9 222 222 222?