Time: 10-10:45pm EST
Frequency: Periodically throughout dungeon
World name: Ultros
Character name: Haran Tracyn, Ruusaan Kar'ta, Fayt Harkwind, Tiz Arrior
NPC name: N/A
Monster name: Various enemies
Class/Level: Haran - 50 WAR, Ruusaan - 50 WHM, Fayt - 50 DRG, Tiz - 50 BRD
Party or solo: Party
In-game time:
Area and coordinates: Amdapor Keep
Steps:
1. Preformed party entered dungeon, minor instances of lag here and there (not too abnormal)
2. Party notices that attacks are not executed properly (i.e. I used Heavy Swing and Flash went off, Ruusaan used Cure II and cast Protect instead and could not interrupt casting by moving)
3. Proceed past Demon Wall. Problems start getting very noticeable after this. A summary from each party member, in their own words:

Haran
Minor lag, no attack execution problems that I was aware of. In a mob of three enemies, Succubus and two Soul Collectors, the third Soul Collector was displayed as dead on my screen, then moments later loaded as fully alive. Targeting issues occured, where I could not target enemies before attacking and pulling and ended up selecting my own party members instead.
During the fight with the final boss, lag spiked and while I could still attack, my party said they saw the disconnect symbol and my damage would not be counted. This eventually lead to a 90k error where I was disconnected from the server, and while I could get back on relatively quickly, it took a very long time for me to load and party described me as T-stancing while I saw the loading screen.
Ruusaan
Overall lag, her heals weren't landing/health bars wouldn't move when they did, Medica 2 buff didn't appear at times despite being cast, could select party members on up/down gamepad but left/right often didn't target anything at all or wouldnt scroll between targets. Showed animation of Haran jumping over the railing in the area after Demon Wall (which is an inaccessible area), but she snapped back into place a second later.
Fayt
Saw an enemy go down and as it died it changed names to the final boss of the dungeon. This is probably a database ID error (i.e. the monster died then cycled to another enemy's ID but was already registered as dead so it was a enemy but ID'd itself as a boss). Upon using Limit Break on the final boss, no damage was registered and the party was defeated.
Tiz
Purple lines that indicate a player has been targeted by Dark Nova were not showing up, Haran T-posed at the end of the dungeon after reconnecting, textures and walls disappeared, people weren't moving at all. During the final boss after tank disconnected, one statue disappeared along with walls/other parts of the room, and there was nothing to hide behind from Dark Nova and Imminent Catastrophe damage and the party died.
Needless to say...this pretty much made the dungeon impossible for us to complete. We can usually clear the dungeon well within 30 minutes, yet this time we ran out of time due to constant errors and problems we have never experienced before. All four of us are on the PS3, none of us usually have internet connection problems (all of our connections were fine during this time). This isn't the first time we've had trouble in a dungeon due to factors out of our control, but even after hotfixes the problems persist - granted not as often, which we are happy for, but it still renders parts of the game unplayable.