It seems these errors are happening most often when moving between instanced servers. For example, MSQ instance quests caused multiple 90k errors and I had to ultimately do them on very easy just to have a HOPE of getting through the content. Add in the que times and everything else took about 10 hours cumulatively to get through a single instance quest which is collectively worse than the issue with Raubahn in Stormblood.
Another point where i hit 90k errors the most happens when I leave a dungeon. Now this can be during the cut scene of a new dungeon (causing the most frustration because it ends it through the disconnect) or simply leaving a dungeon I have run before.
Finally, these can happen when moving between areas or switching instances in an area I am in.
Once these occur I then must wait in a queue length for an hour or more depending on when they occurred (usually an hour after 1pm central time) causing more strife. Of course when attempting to get back in I seem to encounter a large number of 2002 errors that ultimately result in me being pushed to the end of the queue line because the game will not load within the small window needed after an error has occurred to retain my spot in the queue.
These are issues that SE has seemingly liked to chalk up to the "users internet connection" and yet multiple posts and people have provided evidence that this is not the case. I have, in fact, maintained a consistent connection via discord talking through the errors with my friends via the voice chat. If there was an issue with my connection then I would also drop my voice chat at the same time. Of course this doesn't happen because it is happening outside my network and SE has no buffers in place to assist in these packet losses and instead throws out the 90k errors.
These issues have gained momentum since the "fix" of 2002, 4004, and 3001 errors in the most recent hot fix. However, it seems as though very little is being done to resolve these issues. Please take in all the different posts regarding these issues and actually make some concentrated effort into solving them.