I've got a GL-MT1300 that has worked really well for me for ±3 years. In the last two weeks it's learned a new trick: I plug it in, the blue light comes on, and then nothing further happens. The unit doesn't broadcast any SSIDs (neither the default nor the ones I defined). On both 2.4GHz and 5GHz it's just silent. The panel light continues pulsing.
Sometimes power cycling the router makes it work, and sometimes it doesn't.
Sometimes after the router is connected it will fail back to this state; that is, I'll be connected and the router's working and then suddenly my connection to the router will go away.
I'm on a trip right now and don't have access to an Ethernet cable; I can't log in to the wireless admin interface for the obvious reason.
The firmware was updated within the last six months or so but I don't know what version it has. I haven't made any configuration changes in more than a year. It's just worked fine-- so I don't think this is due to a recent change.
Anything else I can try the next time the unit actually lets me connect to it?