Your options:
- Buy a public IP from your ISP if possible.
- VPN provider which can give a public IPv4.
- VPS provider.
You can also use IPv6 if both client and server have IPv6 connectivity.
However, IPv6 tunnel brokers usually need a public IPv4, so in your case it would require native IPv6 on the server side.
If you just need to traverse NAT, SoftEther VPN should be able to do it using 3-rd party servers.