Forticlient: SSL VPN timeout
Happened to be a change I did to /etc/ppp/options to disable IPSec for another native VPN I had. 

I added

plugin L2TP.ppp
l2tpnoipsec 


to connecto to a L2TP/IPSec VPN with only L2TP, but with this change  FortiClient SSL VPN stopped working. 

Commenting out the two lines restored VPN functionality.