I have a direct fiber connection - no modem. My ISP gives me a cat 5 cable to plug directly into my router...
Anyhow,I reviewed the logs. In my Plex server window, it shows my correct public IP address. However, in the logs is shows a different IP address. Strange. I went into my router and noticed it gave my public IP as the one listed in the log. WTH is going on here? After googling turned up nothing, I broke down and chatted with my ISP.
As we all know ISPs are the root of all evil... or stupidity, laziness, or something else bad. It turns out that they are running out of IP addresses and instead of upgrading the network to IPv6, they instituted a CGNAT. I had to google that; it was new to me. Well, that is the source of my problems. It can be resolved for the low, low price of $15 a month for a static IP. But wait, there's more. Since I complained early in the roll out, they will discount my fee to $5 a month if I act now.
Darn people squeezed another $5 a month from me for nothing. And here I thought I got a "free" speed bump from them the other month. That is likely when they instituted the CGNAT.
My advice to others - check for this scenario. The support guy was knowledgeable and friendly. Told me many IPs were doing this right now. It's cheaper and easier than converting to IPv6 and it solves the problem of limited IP addresses in the short term.
Still don't understand why the NAS box with no real configuration at least works with indirect mode and the main server is completely crippled. Is there a way Plex can fix CGNAT issues with software?