I use a Zyxel firewall and The Greenbow on the clients. I've double-checked every value on the firewall and on the clients, it's everything ok. Sometimes I can connect - but most of the time I can't! I get the error:
ipsec_get_keystate: no keystate in ISAKMP SA
I've read the manual, I've searched the net, I've called my ISP, I've asked three IT experts... no one had an idea what is wrong.
I do not know Zyxel firewall but I've worked with GreenBow client. Since this is old post, if you are still interested, let me know in this same thread. If you are, I need more info than just one error line