Are you updating through the wifi update feature on the device or using Garmin Express on a PC? For a long time, when I update my Garmin devices, I always make certain I use Garmin Express and connect my computer to the internet with an Ethernet cable, not wifi. I think it was simply the wifi congestion in my area from neighbors and my very old wifi appliance.

When ever I used wifi, I'd get half way or a little more and it'd stop, then fail several hours later. When I used an Ethernet connection, the update would be over and done in less than 20 minutes, 30 minutes at the outside.

I recently updated my wifi in the house but haven't checked whether the Garmin devices that have their own update feature can successfully update now or that I can successfully update using Garmin Express with a wifi connection to my computer.

Other issues to Garmin servers for update can even be your time and time zone being off on your computers. I had that actually happen once, but in that case I immediately got a message oddly and wrongly stating the Garmin servers were down. But they weren't.