I also have no access to SSH on the server (shared I believe) and this seems to be of quite high importance to the use of mysqldump.
That's likely a problem. If you can get that ssh access then this should sort it out for you.
Give this a read.
https://codex.wordpress.org/Backing_Up_Your_Database#Using_Straight_MySQL_Commands
Which would help you get that access.
Or try one of the backup plugins.
https://wordpress.org/plugins/search.php?q=backup
I use this one myself to backup the whole works to Google Drive.
https://wordpress.org/plugins/updraftplus/
It does it in chunks and I've never had a backup fail. I'm sure the others work that way as well so that may be the solution for you.
Edit: I've also deleted your duplicate topic and moved this one to How-To and Troubleshooting where it belongs.