90002 error codes and extreme lag and delays (20 second delays generally, and as high as 45 second delay for NPC conversations).
It may be worth noting that I have attempted to use WTFast to resolve this (I had similar issues a year ago, and WTFast solved this), however now WTFast only gives me slightly more time before the issues continue.



ISP:
Sky Broadband, Kent, United Kingdom

Type of Internet Connection:
Fiberoptic broadband - Wifi connection

Internet Connection Speed:
Roughly 1.6mb/s


Date & Time:
26/06/2015
All night between 20:30 and 23:30
GMT +-0

Frequency:
Always

Character Name:
Blinky Quick

World:
Odin


Area and Coordinates:
Dravanian Forelands, Sohm Al instance (3 disconnects and severe lag), long delays in all other areas (including Gridania).

Party or Solo:
Both

NPC Name:
Alphineaux in particular, moogles, mobs.

Monster Name:
Any

In-Game Time:
Not known

Steps:
Prior to heavensward I had no issues at all, then heavensward patch loaded, and now I get a lot of lag and delays. It is not constant, I can go hours without lag, but this entire evening has been full of lag. 3 disconnects while trying to queue for Sohm Al (at which points we had spent around 2 and a half hours queueing for an instance in total), another 3 disconnects whilst inside Sohm Al. Heavy lag while fighting mobs in Dravanian Forelands, extremely severe lag while talking to NPCs in the next area and in Gridania.

PC Specs
-=-=-=-=- System Information -=-=-=-=-
OS: Windows 7 64-bit
CPU: Intel(R) Core(TM) i5-4570 CPU @ 3.20GHz
Memory: 8GB RAM
GPU: AMD R9 290 4GB
HDD: 2TB
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-


Information About the Peripherals You Are Using
-Type: Mouse
-Make and Model: Sensei Raw Gaming Mouse

-Type: Keyboard
-Make and Model: Razer Blackwidow Ultimate Stealth