You can not use the web admin interface (device IP) and also use OBiTALK to configure your OBi device(s).
If you want to use OBiTALK, you can make additional changes using the OBiTALK > "OBi Expert Configuration" that will allow you to make changes on most of the OBi device settings that you see when connected to the OBi device admin web page.