OpenVPN client disconnected every second hour

I tried to add the disable-dco option in my ovpn file under the client section:

client
.
.
disable-dco
.
.

But that gives the following error in the log:

daemon.err openvpn(Test)[3375]: Options error: Unrecognized option or missing or extra parameter(s) in /var/etc/openvpn-Test.conf:22: disable-dco (2.5.3)

Please advise of how I can proceed.