Got it eventually. Not sure why but a couple of goes at HTTPS it worked.
Any advice on how to get it to run in transparent mode.
Current setup is ISP--->Mikrotik router (cloud something) -->ciscomanaged switches x 12
There are a couple of VLANS setup within the mikrotik
I'm not wanting anything more than having the Fortigate 200e work in transparent for now until a new guy starts in a couple of weeks.
Checking the config, the subnet 255.255.255.0 is the same as the mikrotik, IP range the last assigned IP is 10.10.10.22 I assume 23 is a sensible choice.
Currently access it via a standalone pc, not networked so its not a great test if it is working or not.
THe ISP router however sits on 192.168.100.2/24 on network 192.168.100.0
post edited by MrAitch - 2020/01/28 17:33:39