Have a /29 with OOL and static IP xxx.xxx.75.240/29.
If you are outside the network, and on a different ISP, and browse to xxx.xxx.75.241 , you end up on the management page for the cable modem.
Seems to be a bit broken as this should be a usable IP
If it were me, I’d contact your ISP about the issue.
I think you will find this is normal, /29 has 6 useable IP’s and one will be the gateway address in this case .241
To use your IP’s you need to setup virtual IP
pfsense Setting Multiple Static WAN IP Addresses / Using Virtual IP’s NAT Firewall Rules - YouTube