"servers unavailable"

You might want to verify that your .Net framework is up to date.  GE won’t run properly without it or if it isn’t functioning properly.

Thanks for the suggestion, but I already have it ( and it is up to date) :/. The device won't pair to the Garmin Connect Android app too.

I also discovered that if I try to enter the serial number in Garmin's Support page it shows an error saying that it can't find this serial number.

Related to this, I also investigated the Garmin Express logs and found several network requests trying to authenticate the device and that are returning errors. It seems that Garmin apps are trying to authenticate my device and are unable to (and are also unable to provide any helpful error message...).

I contacted Garmin support today with all the details to see if they will answer.

"Thanks for the suggestion, but I already have it ( and it is up to date) :/."

Having it and making sure it is running OK may be two different things, especially if you have difficulty with GE even before you attach some device.  There is a .NET Framework Repair Tool at support.microsoft.com/.../microsoft-net-framework-repair-tool-is-available-942a01e3-5b8b-7abb-c166-c34a2f4b612a

Thanks again. It is running ok, every app that depends on it is working normally. In any case, I tried repairing it, but it didn't change the error in Garmin Express (I still get the same request throwing an error in the logs as well).

I have the same problem, On my laptop it used to work, no Garmin says servers unavailable,  Since Garmin started giving all these issues I have been using my Samsun watch.

Call Product Support if none of the suggestions here work. More than likely an issue with your system.

What support?  Garmin does not know about support. And it looks that it is the only thing you can suggest. For years people complain about this errors. That is why I are moving to another watch. Even my Wife's Fitbit is better and have better support. 

I'm having the same problem at the moment on two different PCs.

Some others have the problem, too, see German forum.

I can download my training from the clock with the old Trainingcenter software, but GE is giving a server error.

The same error appears when I try to look for updates in GE.

I have GE 7.13.1 and Windows 10 with all updates.

EDIT:

Deinstalling and re-installing of GE helped!

FYI -- I first posted my 'server unavailable' issues 3 months ago. With no help from Garmin, I just put my devices on the shelf for 3 months. Today, Garmin Express is working for my and registered and updated both of my devices. There has been no change in my system or software (but for windows updates).

So likely a problem with your Windows set up then