GL-MT300A does not expose wifi network?

My GL-MT300A 256MB does not give me the wireless network at one specific geo location!

Usually when I power on the device the red/orage led turns on after a while. At that one specific location the red/orange led never lights up and the wifi network never becomes available.

I have been using this device many times over the last years without problems but now I have a strange problem. At one particular location the device does not boot to the point where it exposes the wireless network. If I walk away 100m from that location and try again the device boots correctly and I see my network.

The location is a large building with many floors and 50+ wifi networks visible, so that could be a cause for the issue. When I test the device is right next to me (not on another floor or in another room) and still I do not see any network.

Question: What can I do to troubleshoot and solve this issue?

I am at this location only once every few weeks, so any tests you suggest might take a while to complete…

Strange. Does someone at the location uses the same MAC address?

You can use software to scan and check if there is another device using your MAC.

You can also connect a cable to the router, then check if the system boot up by ssh to it and check the logs