In many (if not most) cases it is an issue occurring in route to the servers. Your local connection (what gets checked when you call in or a tech comes on site) may be perfectly fine, but that is not likely where the problem is. It is usually out at the pole, down the street... in another city, state, or even country. By default, there can be as many as 62 hops between your system and SE's servers. Every one of those is a potential point of failure.
It may be worth running some tracerts to your server or at least your lobby server to see if there is anything erratic along your route that your ISP needs to look at. Here are the registered DNS names for the lobby servers if you want to use them. Half are in Canada (even numbers), the others in Japan (odd numbers):
neolobby01.ffxiv.com
neolobby02.ffxiv.com
neolobby03.ffxiv.com
neolobby04.ffxiv.com
neolobby05.ffxiv.com
neolobby06.ffxiv.com
Most the time it winds up being an issue between your ISP's peering hand-off to a Tier1 provider, somewhere in that Tier1's own network, or during the hand-off from them into SE's ISP (Ormuco). This CAN be remedied by your ISP either by them reinforcing their peering agreement with that Tier1, or switching you to a different Tier1 provider. Nearly ALL of them have agreements with the big 3 in North America (Level3, TATA, Cogent). Lately, Level3 seems to be the one having the most trouble meeting the demand on their networks.
Important point that needs to be understood, in case some are not aware of just how the internet works. You do NOT have a direct connection to SE, by the way. Your ISP carries you part of the way, then a third party (sometimes even a 4th or 5th) will carry you a large portion of the way (like across the US and into Canada), and then you get handed off to SE's ISP. Your "internet connection" that is getting tested when you call in is your local node---they are in no way checking the complex web of connections that you traverse across the internet to get to this specific server. Note that each site you go to can have a vastly different path at certain portions of your route, so testing against a benchmark site or another game is NOT the same as testing against any of the servers connected to
this game. Hence, you need to run a test against an actual server that is used for
this game.
If you find something in the traces, forward your findings to your ISP's Tier3 Support for escalation. The help-desk and on-site tech's can't really do anything about this--you NEED to get Tier3 involved as they are the ones that can get the proper people to investigate any potential issues concerning your specific route. But, you will need to provide them the specific data they need to get involved--the bulk of that will be covered in your tracert results.
For a sort of visual of the path, here is the one I am currently using to my actual game server. This is the IP address my client actually communicates with when I am playing. Notice how the ends of the names are similar in groups along the path. That is because I am being handed off to a different company's network along the route. Note the last hop in the TWC/rr.com network where I have an asterisk. This is typically where I start running into trouble--around the hand-off into their peering partner that is taking me from the DC/VA area and up into Canada (it periodically stalls like it did here, and I get shot off to an absurd region's server (this one is reserved for use out west) before heading forward up the East Coast towards Canada). I live in Florence, South Carolina... when I call my local office or even the help desk (which is Tier1), they can't diagnose this as it is further up the chain then they are able to investigate. This calls for Tier3 or higher to address.
Code:
Tracing route to 199.91.189.30 over a maximum of 30 hops
0 MJ14336 [10.10.100.2]
1 LPTSRV [10.10.100.1]
2 cpe-066-026-112-001.sc.res.rr.com [66.26.112.1]
3 cpe-024-031-198-005.sc.res.rr.com [24.31.198.5]
4 clmasoutheastmyr-rtr2.sc.rr.com [24.31.196.210]
5 be33.drhmncev01r.southeast.rr.com [24.93.64.180]
6 107.14.19.20
7 * ae-4-0.a0.lax91.tbone.rr.com [66.109.1.113]
8 ix-17-0.tcore2.AEQ-Ashburn.as6453.net [216.6.87.149]
9 if-2-2.tcore1.AEQ-Ashburn.as6453.net [216.6.87.2]
10 64.86.85.1
11 if-10-2.tcore1.TTT-Toronto.as6453.net [64.86.32.33]
12 if-9-9.tcore1.TNK-Toronto.as6453.net [64.86.33.25]
13 if-7-2.tcore1.W6C-Montreal.as6453.net [66.198.96.61]
14 66.198.96.50
15 192.34.76.2
16 199.91.189.234
17 199.91.189.30