aloSIM will automatically choose the best network for you to use, so it's best to leave your "Network Selection" on "Automatic."
Sometimes people are familiar with a certain mobile network, so they decide to configure their network manually and choose their "usual favorite" network from the list. But just because you typically use one provider doesn't mean you should use them with aloSIM.
If you attempt a manual network selection, you may see five or six networks display in the list, but that doesn't mean your aloSIM plan is compatible with all of them.
And if you choose a non-compatible network manually, your data will not work.
That's why it's so important to leave "Network Selection" on "Automatic." That ensures your device is only going to connect to networks supported by your aloSIM data plan.