Make sure that you and your friends are using the same version of the game and Seamless Co-op Mod.
Create Multiplayer Game
Step 1: Install Seamless Co-op LAN Mod Download
Seamless Co-op LAN Mod. Unpack and copy files from "Elden Ring + DLC Multiplayer Mod[Seamless Co-op] (LAN) v1.7.6" folder to Elden Ring game folder.
Step 2: Install Radmin VPN and create a network Download and install
Radmin VPN. In the main Radmin VPN window, click "Create Network".
Enter the network name, password and click "Create".
Step 3: Ask your friends to join the network Send your friends the name of the Radmin VPN network and the password to join to this network.
Step 4: Launch Elden Ring Launch Elden Ring using "ersc_launcher.exe" file.
Step 5: Add the game to the firewall exceptions You need to add rules to the firewall. Open Radmin VPN -> System -> Firewall Exceptions and add Elden Ring to the exceptions.
Step 6: Create game Create your character. Go through the prologue and get "Tiny Great Pot". Activate it by clicking "Esc" -> "Inventory" -> "Tiny Great Pot" -> "Use".
You have now opened your world to external connections. Wait for other participants.
Join Multiplayer Game
Step 1: Install Seamless Co-op LAN Mod Download
Seamless Co-op LAN Mod. Unpack and copy files from "Elden Ring + DLC Multiplayer Mod[Seamless Co-op] (LAN) v1.7.6" folder to Elden Ring game folder.
Step 2: Install Radmin VPN and connect to the network Download and install
Radmin VPN. In the main Radmin VPN window, click "Join Network". Enter the Network Name and Password and click "Join".
Make sure you and your friends are on the same network.
Step 3: Launch Elden Ring Launch Elden Ring using "ersc_launcher.exe" file.
Step 4: Add the game to the firewall exceptions You need to add rules to the firewall. Open Radmin VPN -> System -> Firewall Exceptions and add Elden Ring to the exceptions.
Step 5: Join the game Create your character. Go through the prologue and get "Effigy of Malenia". Activate it by clicking "Esc" -> "Inventory" -> "Effigy of Malenia" -> "Use".
You should be connected to the host.