Need to reboot after idle for a few hours

I’ve been testing a couple of custom end devices sporadically, and have found that the TTN gateway stops responding correctly to the devices after a period of idle time (not sure how long as yet, but some hours). The devices cannot send data with the error EV_JOIN_TXCOMPLETE: no JoinAccept). The TTN dashboard shows the device has been seen, but obviously the response to the join request is not getting back to the device. If I unplug and replug the gateway it starts working again as normal. The gateway is warm to the touch, but not hot.

Is this a known issue? Is there another gateway that can be left idle for extended periods and still forward data ok? I’ve thought about adding a smartplug in front of the gateway and just power-cycling it every hour to ensure it’s working.