@NeillyK65
Thank you very much for the feedback.
1. Make sure your SIM card has been detected by the 4G LTE Router and not locked by PIN code. You could check SIM Card Status on Advanced->Status page to confirm it:
If it shows "No SIM card detected", follow this guide for troubleshooting: https://www.tp-link.com/support/faq/3486/
If it shows "PIN Required", go to Advanced->Network->PIN Management to enter PIN code of your SIM card to unlock it.
2. Verify APN profile settings: Check if the Access Point Name (APN) settings on Advanced->Network->Internet page are correct. If not, try other available profile or create a new profile manually.
3. Factory reset the 4G LTE Router, pressing and holding the reset button for about 10 seconds. Keep in mind that this will erase any customized settings, so make sure to note them down before resetting.
4. If the above suggestions did not resolve the issue, this is a detailed FAQ for more troubleshooting tips: https://www.tp-link.com/support/faq/2842/