Cannot see IPv6 IP settings in advanced Network settings.

This is not a manual function and this is a subject of your ISP. There's absolutely no need to change to IPv6, and it will not solve your NAT issues as that is local.

you need to open up the Network ports on your router

The purpose of IPv6 was to add additional IP address addresses to the Internet. Since you already have an IP address you don't need IPv6

https://support.microsoft.com/en-us/topic/open-these-network-ports-for-xbox-one-94d5f68a-387c-1982-7163-6e12a4d9e981

This will be based on your router, if you have IPV6 available in your area, the console should see it automatically.

If your Xbox One has IPv6 connectivity, your Current Network Status will read
IPv4 & IPv6. (To see your actual IP and gateway addresses, select
Advanced settings.)

https://beta.support.xbox.com/help/Hardware-Network/connect-network/ipv6-on-xbox-one

That page should help a lot.

Hi,! I'm Luis, a fellow Xbox Gamer . Thanks for reaching us out here.

For Xbox to connect to the internet using IPv6, your home router needs to have IPv6 enabled, and your internet service provider (ISP) must support IPv6.

Here’s how to check if your xbox is using IPv6:

Press the Xbox button  on your controller to open the guide.

Select Profile & system > Settings > General.

Select Network settings.

If your Xbox console has IPv6 connectivity, your Current Network Status will read IPv4 & IPv6. (To see your actual IP and gateway addresses, select Advanced settings.)

It'll generally just show the IPv4 IP address on the main screen, but you can check if it's IPv6 enabled by going to Settings>Network>Advanced Settings.

This page has more details on IPv6 for Xbox One. Do you have access to get to the router management page, or is it wholly
managed by Spectrum?

Thank you for contact us! I'm Anderson, an Independent Consultant and a Microsoft user like you.

Good afternoon

try changing your xbox's IPV4 and IPV6 settings.

Power on your Xbox and press the Xbox button on your controller to open the guide.

Go to "Profile & system" and then select "Settings".

From the Settings menu, select "Network".

Under the Network menu, select "Network settings".

Select "Advanced settings".

Under the Advanced settings, select "IP settings".

From here, you can toggle between IPV4 and IPV6 settings by selecting the respective option and changing the settings as per your requirements.