Hi,

View /etc/inc/openvpn.inc.

Locate the several function calls and definition at the bottom of the function called : openvpn_add_keyfile

This function takes the directory, the extension, the PEM based64 encoded data and writes out the file.
File rights are set to 0600 and that's it.
It's line 760 in the openvpn.inc file.

If something goes wrong at that place, I guess the $data that gets base64 decodes isn't 'ok' ?
Is your cert ok ?
Many cert type files are created using that function. When only "server1.cert" goes wrong, I gues it's input (= $data) is 'wrong'.

An old 2.4.4-p3 bug that got resolved (?) ^^
edit : non. openvpn server was working just for for my when I was using 2.4.4-p3.