The HA is hard wired directly into my Cox modem/router. I have completely disconnected and unplugged my other router to avoid confusion. There is no VPN.
Attached is what i get when I ping homeassistant.local -4 in CMD
It does not complete the scan. all I get is what I sent then the screen disappears.
Lets set the HA device to DHCP in your Cox router, reboot the router and run the CMD ping again. With it being connected directly you should at least get a reply.
Was your IP manually set here?
My instincts tells me this is network issue and not a HA issue. What is the model of the COX device? I ask because there may be way to delete the static IP devices.
after multiple trys and reboots, i got it to stay in DHCP.
I ran another CMD ping and got a response. see screenshot below.
Does this work now from a browser?
http://192.168.0.51:8123
it does not. i tried two different web browsers but both say it refused to connect.
Same with http://homeassistant.local:8123 ?
both don’t work 
Your HA is talking to your network, we know that. What is your installation setup? Is it Docker as I remember?
What device is hosting HA?
Sorry have been answering multiple threads. HA green… DUH
haha no worries!
These are true?
especially the LED portion
and what do you get from the PC you are trying to access HA from when you enter
ipconfig in CMD?
all true. The green light flashes rapidly where the ethernet cable is plugged into and the green light on the front blinks slowly at the same rate.
yellow led on front blinks in a heartbeat pattern.
below is what i get when i enter the command.
You have something odd going on with your IPv6. Try temporarily disabling it on the PC adapter.
Typical reply
Was IP forwarding enabled on your router when you enabled port forwarding?
I am unsure if IP forwarding was already enabled.
Your router isn’t making the connection between HA and your PC so I think its a router setting. Can you disable port forwarding?
COX routers are a pain in the butt 
This would be my last resort