Okay, so browsing r/FFXIV (for what it's worth) did yield some promising results. One user said they spoke with someone from NTT about it, and here's what was posted. (Edit: Link to the r/ffxiv thread for proof: https://www.reddit.com/r/ffxiv/comme...on_east_coast/ )
"This is in relation to a prime-time congestion issue when AT&T's network hands traffic over to NTT which is the last provider in the hop before anyone in AT&T's network will get to the game servers. I contacted NTT's NOC about this several hours ago and received the following reply:
This is due to a known congestion issue between us and AT&T which is already being investigated. Efforts are ongoing to alleviate the congestion but due to NDA, the GIN NOC is unable to disclose any specific details.
So take heart that the folks responsible for the network are already aware of this, and the problem is wholly out of Square Enix's hands."
TLDR; NTT and AT&T are aware of the node's issues and working on it, but cannot elaborate further due to obvious NDAs.
At least they are aware of it, but we should keep the reports coming.