Unfortunately there is not yet an official way to enter APNs manually in Android Wear 2.0. So this is nothing LG specific - the same is for other smartwatches like the Huawei Watch 2 4G. As the virtual provider's (MVNO) APNs are usually not preconfigured you won't be able to connect. At the moment the only way to circumvent this is by rooting your watch. In my blog post I describe the process: