Concrete proof finally provided that the 2002 error has NOTHING is server side issue

[ArkenaeuxBelmont]

I don't really think OP has any concrete proof.
Basically Japanese side agreed this is client side issue (player) and suggested the following 3 methods (copy word to word)

対策方法1：WiFiの接続方法をIEEE802.11nに変える
もし11acで無線接続している場合は通信品質が悪いことが多いので、速度が気になるところですが11nで接続しなおしましょう。
11acは通信速度が速い特性がありますが、障害物に弱い
11nは11acよりも通信速度は遅いが、障害物に強い
障害物を超えるごとに電波はどんどん弱くなっていきます。

This is to suggest to change type of WIFI connection from 11ac to 11n and basically concluded:
11a provides higher speed but signal will be weaker if there are obstacle (like metallic/concrete object)
11n is slower but stronger if there are obstacles

対策方法2：次世代通信方式11axが使えるルーターに変える
11axは超高速通信規格でWi-Fi 6と呼ばれるものです。
11axは「11acと11nの良いとこどり＆通信速度が速い性質の電波」で通信品質も格別です。

This method is to suggest to switch to WiFi - 6

対策方法3：LANケーブルで接続する
まあ、確実ですね…。
ルーターが近くにあってパソコンやPS4と接続可能であれば検討してみてください。
なお、LANケーブルは見た目は全く同じでも規格があり、古すぎると通信速度・品質に影響が出る場合があります。

Last method is to suggest is to just abandon wifi and use direct cable connection.
Simple and straight foward.

They also suggest to not have anti-virus program to be running at back ground.

After SE patch, I am experiencing only 2 x 2002 from previous 8 x 2002.
This is my computer environment:

This new i7 CPU with 3080 GPU is connect via direct cable, no wifi
As the system is for gaming only (no surfing, no youtube), there is no anti virus program since i am not installing anything beside steam games.
My router is pretty old that bought 6 years ago and i assume that is why i am still encounter 2002 occasionally
I bought the new wifi6 router and will see if i am still having 2002 after installation

Did you read the google doc and the investigation the person did?

[Divinemights]

Did you read the google doc and the investigation the person did?

Yes, I did.
It is a theory, not a proof.
I also said it is suggestions because whatever Japanese is suggest is also a theory
No IT tech is able to recreate same environment for each player's system
I only can tell you SE is not intend to lie about 2002 because their IT is truly believed it is client side issue.
This is a blog from a Japanese player in regard to 2002 at year 2014 (not provide name due to privacy:

2014/02/06 09:49 3
ロビーサーバー接続でエラー2002の対処法
[エラー2002]
公開
昨日からエラーで入れなかった件ですが

GAME　START

をクリックしましてデータセンターに接続表示後

ロビーサーバー接続でエラーが発生しました（2002）

と出て入れなかったわけですが

問い合わせメールの返信が来ました。内容は最後にコピペしときます。

自分の原因はですがセキュリティーソフトのバグ？でした。

普通でない状態だったらしく立ち上げて更新とかクイックスキャンとかできることを片っ端からやって閉じたら

FF14に入れるようになってました。このエラーは向こうに原因はなくPCか回線の問題みたいですね。

ともかく入れてよかった。


ではコピペ

Basically, SE IT tech inform him 2002 is player's PC connection issue and this JP player fixed it by turn off the antivirus program: there is a bug with security soft (セキュリティーソフトのバグ)

After the patch, I on average only encounter 2002 twice and my system environment is cleaner than most of FF14 players because this system is dedicate to gaming only. No other 3rd party software including discord. I bought the new wifi6 router, i will update if i am still getting same 2002 frequency
The question is, as a game producer, who should Yoship believe? His own IT tech team who able to provide steady service before WoW exodus or some google document and no idea who the author is?

[Darthgummibear]

Yes, I did.
It is a theory, not a proof.
I also said it is suggestions because whatever Japanese is suggest is also a theory
No IT tech is able to recreate same environment for each player's system
I only can tell you SE is not intend to lie about 2002 because their IT is truly believed it is client side issue.
This is a blog from a Japanese player in regard to 2002 at year 2014 (not provide name due to privacy:

2014/02/06 09:49 3
ロビーサーバー接続でエラー2002の対処法
[エラー2002]
公開
昨日からエラーで入れなかった件ですが

GAME　START

をクリックしましてデータセンターに接続表示後

ロビーサーバー接続でエラーが発生しました（2002）

と出て入れなかったわけですが

問い合わせメールの返信が来ました。内容は最後にコピペしときます。

自分の原因はですがセキュリティーソフトのバグ？でした。

普通でない状態だったらしく立ち上げて更新とかクイックスキャンとかできることを片っ端からやって閉じたら

FF14に入れるようになってました。このエラーは向こうに原因はなくPCか回線の問題みたいですね。

ともかく入れてよかった。


ではコピペ

Basically, SE IT tech inform him 2002 is player's PC connection issue and this JP player fixed it by turn off the antivirus program: there is a bug with security soft (セキュリティーソフトのバグ)

After the patch, I on average only encounter 2002 twice and my system environment is cleaner than most of FF14 players because this system is dedicate to gaming only. No other 3rd party software including discord. I bought the new wifi6 router, i will update if i am still getting same 2002 frequency
The question is, as a game producer, who should Yoship believe? His own IT tech team who able to provide steady service before WoW exodus or some google document and no idea who the author is?

You're seriously going to cherry pick a single example from SEVEN YEARS AGO as if it has any relevance whatsoever to the problem at hand?

[Divinemights]

You're seriously going to cherry pick a single example from SEVEN YEARS AGO as if it has any relevance whatsoever to the problem at hand?

No?
Just showing that is really what their IT believed in?
Is Yoship an IT or a game producer?
Better question is, are you a person believe in professional IT or something you googled?

[Darthgummibear]

No?
Just showing that is really what their IT believed in?
Is Yoship an IT or a game producer?
Better question is, are you a person believe in professional IT or something you googled?

Did you actually read the entire question?