The option "comp-lzo no" is considered depricated and will not be supported by future OpenVPN clientsor servers. Don't use this option on your server.
The recommendation of the OpenVPN developers is to best not use this option at all anymore. It is better toeither activate compression ("comp-lzo yes"), or to not use any compression at all (in this case the option "comp-lzo" should not even appearin the configuration).
The Optiome "comp-lzo no" doesn't mean "no compression", it means "compression only if the server requests it." Because of this the "comp-lzo" option is being replaced by the new option "compress", which partially shows a different behavior and thus is not backward compatible.