@TimStewart 

The possibility of replacing the external antennas on your TP-Link LTE Gateway router depends on the model. TP-Link LTE Gateway routers have two types of external antennas: LTE antennas and Wi-Fi antennas.

If your router has two undetachable external Wi-Fi antennas, they cannot be replaced. However, if your router has two detachable external 4G LTE antennas, you can replace them.

When replacing the 4G LTE antennas, there are a few important considerations:

1. Both antennas should be changed simultaneously with antennas that have the same specifications.

2. The replacement antennas should have the same interface type (SMA male) and support the same frequency range as the original antennas.

3. It's crucial to maintain the distance between the new antennas, ensuring that it is not less than the distance between the original antennas.

Please note that installing third-party antennas may impact device performance and compatibility, and we cannot guarantee the performance of the device after such installations.

For more detailed information, you can refer to this thread: A Comprehensive Guide to LTE Gateway Router External Antennas