Why can't the mobile app upload a ride to Strava all by itself? When Garmin's server is down it can't do anything. This happens too frequently. Also, why isn't there a backup server?
Why can't the mobile app upload a ride to Strava all by itself?
Because Strava connects to Garmin's API on their servers to get the data. If the server is down, you can upload the fit file of the activity to Strava manually. However, it did not happen to me since perhaps two years, and I log in average 5-6 activities per day. I suspect that in your case it is rather either a problem of local Internet connectivity, or a lost connection between the watch and the phone.
I think Edge 130+ does not have the USB port, so indeed you cannot download the file from it directly, unless you have an ANT+ stick on your computer, but if (or when) the activity synced to your Garmin Connect account, open the activity in GC Web, export it as "original", unzip it, and import the FIT file to Strava.