[Windows 10 client] 503 Service unavailable when syncrhonizing some files

Hello everyone.
I have got an issue when my files are synchronizing on my laptop. On some files, there is a message indicating the following: “503 service unavailable a GET “https://…a link to a certain file”” canceled operation.
I droped the connection and created it again, but the problem persists.
I do not know if the issue is with those files or is server related.
I will appreciate your help.

you can try a

tail -f /var/log/apache2/error.log

while synchronizing

Thanks for your answer, however how do I find this folder on a Windows enviroment?

You can’t. You need to ssh to the server.

Now is working.