If no push-route has been configured in the configuration it should default to setting route=default in the ocserv.conf file.
Right now it will set a number of route entries in ocserv.conf:
This will not affect connections done with openconnect server, but Cisco AnyConnect will report a missconfigured server and refuse to connect.
set vpn openconnect network-settings push-route '0.0.0.0/0'
The ocserv.conf file will have a correct setting of route = default