We have a network of over 300 RB951Ui-2nD routers with hotspots setup on various locations around Greece. We are in the process of upgrading them and installing new features for our clients.

We have created a script that does all that by reset configuration (no default settings) and running on boot.

We try the script through our vpn, on routers we have in our office and it works like a charm 100% of the time.
The script applies all settings, creates hotspots, starts wlan, connects to the vpn. Basically, it sets everything up and it seems to work fine.
Then we send the same script that worked to other routers. About 1/3 brakes in random places. Others don't take any settings. Others just refuse to start wlan. It basically is a random occurence.

We take care that all routers are updated to the latest Router OS, 6.35.2 before we try the upgrade.

We have tried just sending basic VPN connect setup on startup, but again the same thing happens.

We have tried sending the scripts with FTP, Drag n Drop in Files, through /tool fetch command. Again the same thing. 1 in 3 fails miserably.

The only difference is that some locations may have users on it while reseting, but I don't see what could be the problem with that, since it reboots and closes all connections and when it comes back it just runs the script.

Any ideas? We are stack and cannot seem to find a solution.

Try adding a small (1 to 5 second) delay at the beginning of the script. It is possible that the script executes before system has finished loading all physical interfaces.

Haven't tried that one out. Thanks. Will do and see if that solves it.

The issue was solved by putting delays on startup and on a few other points. After setting time servers for example so that schedules defined in the script work without problems or after setting a pptp client for VPN connection.