Ps5 internet connection issue

[Willjohns]

So, my PS5 doesn’t want to hook up on the network. It says

Can’t connect to the internet. The Ps5 doesn’t support IPv6-only networks. Select a network that supports IPv4.

What do I do?
I am on fiber not cable. Everything else is running smooth as silk. Just the damn PlayStation not working.

I reset my network ( same as resetting your modem and router with cable)
I reset my Ps5
I connected an Ethernet cord from a WiFi extender that sits directly behind the Ps5 and same error.

ISP folks say they have no clue as everything else is fine, so it must be your Ps5