DHCP to Static issues

OK. So I am at my wits end. We have two comcast feeds with 50/10 and 13 static IPs. The DHCP computers cannot talk reliably to the static IPs.  About 8 months ago, we swapped out the comcast tower routers for the SMC 3DG routers and things started working again. Unfortunately, the installed used SMC boxes and one has died.  They replaced it with the comcast tower router and now we are in the same situation. We cannot get to the static IPs from the DHCP computers from either comcast feed now!   Bridge mode does not solve the problem as it will not allow the use of the static IPs. Please help. The SMC box knows how to do this..but not the new comcast tower router with wifi.  PLEASE HELP. We are out of business!!!