This TP-link Outdoor access point is one month old and it's reset itself back to factory settings four times. I've just now set it up again and it did the same two days ago. (It was off for a week and I didn't notice).

The unit is on a timber beam two metres off the ground (pic).

It's powered with the charger supplied via a continuous all new outdoor spec Ethernet cable 

Although the UK weather just now is generally wet the unit benefits from the protection of a roof overhang. 

I wouldn't say that the mains power supply is in anyway remarkable or flakey. There are other devices eg an Ethernet switch, a Hue hub and my Mac running off the same Ethernet and mains cables. 

I have just now replaced an older ethernet cable and if you don't hear from me that was the problem.  

The TPlink EAP110 outdoor needs to reach a security camera 100m away. That much it does. I'm posting this in the hope of finding the collective knowledge.