Constant connection drop

My ISP is Cox Communications. Cable internet, 5+MB speed. Main character is Khonda Sha'lassan on Brynhildr, Primal Data Center.

Ever since December I have had constant disconnect issues. Yes I know I still play on ps3 and yes I know it will be discontinued but still. At first it disconnected every hour after logging in. Then it disconnected me every few minutes. Completely unplayable. I actually tethered my phone to play but that has latency issues as the signal wouldn't be as strong as a home internet connection.

Things I've done to try and improve this:
Set router to static IP
Change security settings
Place ps3 closer to router
Connected directly by ethernet cable
Traded for a whole NEW router
Called the ISP (they insist it's playstation or the game itself)
Connected with other games on ps3...literally every other game connects fine and stays connected
Set my router to fixed channels instead of rotating channels

But here's a curious thing I just discovered:
I experience this disconnect on all of my characters. I rolled on other servers or other data centers just in case it was Bryn or Primal specifically. Well I still get disconnected on Leviathan and still get disconnected on Balmung over on Aether Data Center.

However...

...for laughs, I rolled on Mana Data Center. For players in Japan. On Hades. Because that was my world I played on with Final Fantasy XI back in 2004 all through the merger with Cerberus. And it stays connected! The other night I stayed connected for FOUR HOURS with no problems until I was done. Tonight, just to experiment, I'm not even actually playing I'm just testing a theory here to try and help you guys provide optimal service to players. So far tonight, it's been almost two hours and I'm still logged in just fine. I know some players will be like "grrrr i can't stand people that afk instead of logging yarrrrwharrgarrble" but this isn't to be a jerk. This is for science.

So I'm wondering how everything else works fine on this internet and this router, that both NA data centers CONSTANTLY disconnect, but a data center for JP players gives me absolutely zero issue. Once again, I repeat, I got my constant disconnect issues even before the data center move, and it persists now after the move, and it's the reason I didn't renew my sub for a while. Because it was no longer comfortably playable.

I contacted support once and they gave me some recommendations like clearing the ps3's browser history and cookies and yadda yadda and it seemed to help as it didn't boot me every five minutes, but went back to booting me every hour.

But so far, Mana Data Center on Hades has not booted me. Not even once.

I mean it's cool and all, but rather pointless as most of my friends are on Brynhildr, and I love the RP community of Balmung. So being here on Hades, recommended for players not of my country or my language, is rather pointless.

I don't expect anything to be done about this, as most will probably say "Well when you upgrade to ps4 or PC it should disappear" but that doesn't explain why it works FINE on a Data Center that's supposed to be LESS stable for someone in my location? It's the principle. It's the mystery. I don't expect people without my curiosity to understand.

Hopefully this helps you look into additional things to provide an overall better experience for your players. And hopefully once I get ps4 or upgrade the PC I can come back and I won't have this issue. But until then, I'm done. Because there's just no point playing by myself on a server not meant for me anyway.