Strict NAT detected. NAT-PMP not detected. Please forward UDP ports. (2 PS4s on the same network)

[(PSN)The_Spurginator]

I just got a PS4 a few days ago, which meant I could play Warframe on my own device instead of my roommate's, and we could try to play together. We tried to play together today, and I ran into the error "Strict NAT detected. NAT-PMP not detected. Please forward UDP ports 4950 & 4955 to [IP]. 

1. The immediate help window gave me this help document (which incorrectly refers to PCs instead of PS4s; it's probably interchangeable, but it's still incorrect). The instructions said to pick a different pair of ports. So I picked different ports. Still getting the error.
2. Instead of following the provided documents, I did what the prompt told me to do and looked into port forwarding (I found it interesting that port forwarding is actually not mentioned in the help documents, and picking different ports is not mentioned in the prompt). I gave my PS4 a static IP, picked a new pair of ports, and forwarded those ports to the static IP. My roommate got the error instead, since we'd both restarted our PS4s.
3. So I gave my roommate a static IP, and forwarded the default ports to his static IP. Whoever logs in last still gets the error.

The only solution I haven't really deeply looked into is DMZ, but that doesn't look like a solution I should happily embrace. 

Are there any other solutions? Anything I might have messed up? Is this perhaps actually a bug that was introduced recently? A few hours of searching gave me multiple results, and I'm still unable to figure this out. Not many of my search results came from the last few months, and many of those do not have answers.

I'm guessing my router is relevant. It's a Linksys E1200, running the most recent firmware for its hardware version. Let me know if any other information is relevant. Any help is appreciated.

[(PSN)warkantos]

I have this problem too in my house.

I fix this using this configuration with static ip

Ps4[1] - Dmz

Ps4[2] - Forward UDP

 

[(PSN)The_Spurginator]

I just tried it, and we're still getting it. Perhaps there's some combination we didn't try that somehow works, like switching which PS4 has the DMZ, but I feel like DMZ is just too many hoops to jump through to begin with. I'm reposting this in the Bugs section to see if anyone there knows anything: