Keep in mind that there are two ways to make changes to an OBi device: via the OBiTALK portal, or via the device's local web page (e.g. 192.168.x.x). If you make a change on the local web page, it will be overwritten by the OBiTALK portal, unless you disable that function.
Log into your OBiTALK portal, and go to Expert mode for your device. Go to the System Management page.
The defaults look like my attached screenshot, and should work fine, not causing any problems.