Hello@BNewt ,

This usually indicates that the powerline connection between your adapters is unstable or not maintained, possibly due to electrical wiring problem  or placement. Here’s what you can do to resolve this:
1. Plug both powerline adapters directly into wall outlets on the same electrical circuit (within the same home wiring system). Avoid plugging them into power strips, surge protectors, or extension cords, as these can block or weaken the powerline signal.

2. Reset both powerline devices and try pairing them again. For reset instructions, see: How to Reset the Powerline Adapter to Factory Default

3. Use the tpPLC Utility to help pair and manage your powerline devices. You can find the guide here: How to add a device to the network using tpPLC Utility

4. Make sure both adapters are running the latest firmware, as updates can resolve known issues. After upgrading, attempt to pair them again. Firmware upgrade guidance: How to upgrade firmware of TP-Link Powerline Adapter

If the powerline LED still turns off after a few minutes, it may indicate that the electrical wiring between your main house and the sleepout does not support a stable powerline connection (for example, they may be on different circuits or separated by a breaker box).