Kev_newcastle,   The issue your seeing is due to SupportAssist requiring you use the HOST NIC to talk to the Dell backend, it uses the iSM to send the instructions to go out to the Host Nic then to the internet.   Let me know if this helps.    
I'm trying to setup SupportAssist on several iDRAC 9 cards. USB pass through has been enabled. iDRAC Service Module (3.5.1) is running. When i try to open SupportAssist on the iDRAC I am prompted to retry network connection. Using either direct connection or through a proxy neither works. I've had the firewall and the proxy monitored and nothing hits them. I used putty to SSH onto the iDRAC, I can ping both. I pinged dell.com and it showed up on the firewall (blocked to 143.166.135.105). I've tried this on 2 different cards, with the same result. Anyone any idea what else i can try? While searching for an answer I get a lot of hits from SupportAssist Enterprise - is this to replace OpenManage Enterprise? Thanks in advance any help would be appreciated.
iDRAC 9 support assist fails to communicate with Dell