Authentication Fails Sometimes

so i set up my two servers to sync files between them, everything is going well but the authentication fails randomly sometimes but works around half the time. I have it set to sync every minute. I attach it below just pressing run on my task scheduler, it wasnt running before, first one fails, second one worked thir done failed fourth one failed fifth and sixth worked etc..

c:\sync>echo Thu 09/07/2017 12:40:11.03
Thu 09/07/2017 12:40:11.03

c:\sync>winscp.com /script=sync.txt
Searching for host...
Connecting to host...
Authenticating...
Using username "Username".
Authenticating with public key "key".
Network error: Software caused connection abort
Authentication log (see session log for details):
Using username "Username".
Authenticating with public key "key".


Authentication failed.

c:\sync>exit

C:\Windows\system32>C:

C:\Windows\system32>cd c:\sync

c:\sync>echo Thu 09/07/2017 12:40:17.48
Thu 09/07/2017 12:40:17.48

c:\sync>winscp.com /script=sync.txt
Searching for host...
Connecting to host...
Authenticating...
Using username "Username".
Authenticating with public key "key".
Authenticated.
Starting the session...
Session started.
Active session: [1] Username@servername
Comparing...

Did you check server-side log?