If you can't forward a port it won't work. So get a proper router that allows you that if you ISP doesn't force you to use their hardware.
If you just don't understand how to do a working port-forward its better if you keep it as it is because then you probably also don't know how to secure your PVE (2FA, fail2ban, IDS/IPS firewall infront of PVE, DMZ, VPN, ...) so it doesn't get hacked when being accessible from the internet.