.dll error or server is full error:
whitelist your Ephinea installation folder in your antivirus settings.
Here's a guide to whitelisting for Windows Defender:
https://support.microsoft.com/en-us/help/4028485/windows-10-add-an-exclusion-to-windows-defender-antivirus

Guide for absolute beginners (new to PSO): https://ephinea.pioneer2.net/beginners-guide/

Ephinea Server Information:
https://ephinea.pioneer2.net/about-ephinea/

Forum and Server Rules:
https://www.pioneer2.net/community/threads/ephinea-forum-and-server-rules.2026/

Server and Game FAQ(WIP) + Quick Question, Quick Answer thread:
https://www.pioneer2.net/community/threads/frequently-asked-questions-work-in-progress.5809/

List of Informative Topics/Guides (Section-ID guide, Mag guide, Mechanics guides, etc):
https://www.pioneer2.net/community/threads/list-of-informative-topics.342/

"Box Run" Meseta & Hit Guide for New Players:
https://www.pioneer2.net/community/threads/box-run-meseta-hit-guide-for-new-players-veterans.7117/#post-67874

DropChecker/CharacterReader Install Guide:
https://www.pioneer2.net/community/threads/peppercats-guide-on-how-to-install-the-psobb-character-reader-addon-for-silly-bees.5597/

Echelon's PSO Skins & Mods:
https://www.pioneer2.net/community/threads/echelons-skins-modifications.4357/

PSO:BB Post Processing Mod:
https://www.pioneer2.net/community/threads/psobb-post-processing.721/

Fix for "Game crashing on ranged attack" bug:
https://www.pioneer2.net/community/threads/game-crashing-on-ranged-attack.1298/#post-13082

ATA Calculator:
http://legacywiki.schtserv.com/atacalc.php

Firefox Crash thread:
https://www.pioneer2.net/community/threads/game-crashing-alot.5283/#post-52430

Dotum Font:
https://cooltext.com/Download-Font-%EB%8F%8B%EC%9B%80+Dotum

Phantasmal World Quest Reader by Wilhuf:
http://www.phantasmal.world/

Pricecheck Guide:
https://www.pioneer2.net/community/threads/the-price-check-compendium.5781/