This issue has been happening a lot lately and it's inconvenient.
When somebody tries to join me on a server, AWSD doesn't work for them in-game and they can only use Click-to-Move.
I've managed to trigger this with 2011 and 2009 clients, and I can't seem to find out what's going on.
I've hosted with and without graphics, and I have an entry in the firewall for Novetus and the Client/Server exes.
My Antivirus has an exception for Novetus's Folder Directory.

I have admin privs and I'm not running in a folder like the Desktop or Program Files.

I've attempted to run Novetus with and without admin.

I'm using 1.1, just because it's compatible with old mods, but I'm planning to go to 1.2 at some point.

I use 1.1 so I can play with my friend (easily fixable) and because I use old client mods (I'm porting them right now and they seem functional for the most part).

I've also cleared everything I could find in %appdata%/roblox and %localappdata%/roblox but no dice.

I've also tried with 1.2.4.1, nothing.

EDIT: Clarifications

edit 2: more clarifications