static IP issue

Hello All,

I have a strange issue that I'm having problem explaining to support. We have been assigned IP address range x.x.x.248/29. Our gateway/modem address is x.x.x.254 and the onsite firewall was configured with x.x.x.249 address, with other services FTP, SFTP, SNMP, VPN assigned to addresses 250 and 253. At some point, couple of days ago our network was not able to use any of the connections other than web access (working fine with failover Verizon connection). With suggestion of one of very helpful Comcast techs we switched firewall address to x.x.x.251 and this has resolved most of our issues. The problem is that it seems that the address x.x.x.249 is no longer usable for our company. 

We have had this problem before. The FTP, SFTP, SNMP and VPN all had their own IP addresses assign with port forwarding . One day 251 and 252 dropped. We had to change DNS configuration and shift assignments. It seems it has happened again. Now we lost 249, and 251 IP address is back online.

Comcast support lv2 was not able to ping 249, but lv1 was, so now I'm told the problem is on our end. I don't think that shuffling our IP assignments is a solution to this problem. Has anyone experienced something like this before? What is the best action in dealing with Comcast support.

Thank you. 

Mark