New firewall being set up behind cable modem - What mode should cable modem use?

Getting new firewall to replace old one, setting it up behind Comcast cable modem?  Business has one static IP address from Comcast.  Have recently had issues with site-to-site VPN on old setup, want to make sure I have cable modem in correct mode for new setup.  Firewall vendor says to place modem in Bridge mode, but Comcast forum article at https://forums.businesshelp.comcast.com/conversations/equipment/true-bridge-mode-vs-passthrough-mode/5fe0a58dc5375f08cd7d88fe?linkId=121025033,159985803  says to use Pass-Through Mode when customer has static IP.  

Which mode should I use?  Current Gateway > Firewall > IPv4 settings on modem are Custom Security, Block ICMP, LAN-to-WAN (Allow All), WAN-to-LAN (IDS Enabled and block as per selections below).  According to article above, not quite in true pass-through mode.

Thank you.