You would be better of to switch provider. ISP should have one purpose, provide internet access, not control what you do with it. Here they don't even block SMB

You would be better of to switch provider. ISP should have one purpose, provide internet access, not control what you do with it. Here they don't even block SMB, let alone other services. If one couldn't open services to the outside ISP would be out of business, in an era of IoT, almost everyone I know has at least one webcam exposed. Is it secure? well, depends on the person who set up the thing. Blocking common ports it's a router feature, but you can turn it off. Just stay away from those shady ISPs. I've been running my own HTTPS server, SSH bastion host and VPN without any issue for years.