Hello,
Thank you for reaching out!
It seems like at least for now, Telstra is using a 5G NSA network, which works by first connecting the device to an LTE cell, and then transferring to 5G. This means, that setting the device to 5G-only will not work, and it needs to be left either on Auto, or 4G + 5G.
Make sure there is a good connection and a 5G cell not too far.
If these steps don't help, I'd like you to navigate to System → Administration → Troubleshoot and generate a Troubleshoot file. It can be attached to your original post and will only be visible to Teltonika moderators. This will give me some more insights into the issue you're facing.
Best regards,
DaumantasG
