I got it to work with Bitdefender! Here's what I did!
1. Right Click Rust in Steam and hit "Delete Local Content" (This will uninstall the game.
2. Then, open up C:\Program Files (x86)\Steam\steamapps\common\ and you will see Rust, right click it and hit "Delete", wipe your Recycle Bin.
3. Restart your computer and open CCleaner (
https://www.piriform.com/ccleaner) and run the cleaner and registry.
4. Restart again.
5. Now, open Steam and reinstall Rust BUT BEFORE LAUNCHING IT go into your Bit Defender firewall exceptions settings and add both the legacy Rust.exe and Experimental Rust.exe' as well as Easy Anti-Cheat Setup.exe, etc.
6. Run Easy Anti-Cheat Setup after it's been added to your firewall exceptions.
7. Boot experimental and thank the gods. (:
Hope this helps!