GUIDE PCem Helper — Online Multiplayer Setup Guide

PCem Helper — Online Multiplayer Setup Guide for Pcem Emulator

PCem Helper allows PCem games to communicate over the Internet through the Siljo Planet relay service.

The helper supports:

• TCP/IP games
• IPX/SPX games
• Direct UDP transport for minimal latency
• WebSocket fallback
• Standard PCAP network adapters
• A dedicated localhost wpcap.dll mode

Players do not need to configure port forwarding. The helper uses outgoing connections to the Siljo Planet relay.

Download PCem Helper

You will also need Npcap.

Extract the portable package to a normal folder, for example:

C:\Games\PCEm-Helper\

The portable folder should contain:

pcem-helper.exe
config.json
siljo-wpcap-x86.dll

Do not remove siljo-wpcap-x86.dll. It is required when using the localhost connection mode.

Requirements

You need:

• PCem for Windows
• A PCem virtual machine with a supported network card
• The same game installed on both virtual machines
• PCem Helper on both computers
• Npcap when using the Network Adapter mode

For most PCem configurations, use an NE2000-compatible network card inside PCem.

Connection modes

PCem Helper offers two ways to communicate with PCem.

1. Network Adapter — recommended

This mode captures PCem network traffic through an Npcap-compatible network adapter.

Use this mode when PCem already works with your physical or virtual network adapter.

Requirements:

• Npcap must be installed.
• The same PCAP/NE2000 adapter must be selected in PCem and PCem Helper.

Example:

PCem network adapter:
Realtek PCIe GbE Family Controller

PCem Helper adapter:
Realtek PCIe GbE Family Controller

Do not select Wi-Fi in one application and Ethernet in the other.

Same-LAN warning

When testing two computers on the same physical network, the game may receive packets through both:

the local network
and
the Internet relay

This can produce duplicated packets or additional lag.

For same-LAN testing, the localhost wpcap.dll mode is usually cleaner.

2. Localhost wpcap.dll

This mode bypasses physical network adapters.

The packet path becomes:

PCem
→ localhost wpcap.dll
→ PCem Helper
→ Siljo Planet relay
→ remote PCem Helper
→ remote PCem

This mode does not require:

• Npcap capture
• TAP adapters
• Microsoft Loopback adapters
• A physical Ethernet adapter
• A direct local-network path

When this mode is selected, PCem must be launched from PCem Helper.

The helper automatically copies:

siljo-wpcap-x86.dll

into the PCem folder under the required name:

wpcap.dll

If another wpcap.dll already exists, the helper saves it as:

wpcap.original.dll

When you switch back to Network Adapter mode, the original DLL is restored automatically.

Inside PCem, select:

Siljo Planet Relay (localhost)

as the PCAP/NE2000 adapter.

Recommended guest TCP/IP configuration

For a two-player TCP/IP game, configure the guest operating systems with static IP addresses.

Player 1 / Host

IP address:  10.77.0.60
Subnet mask: 255.255.255.0
Gateway:     leave empty
DNS:         leave empty

Player 2 / Joining player

IP address:  10.77.0.61
Subnet mask: 255.255.255.0
Gateway:     leave empty
DNS:         leave empty

The addresses must be different, but both must be in the same subnet.

Do not use the real IP address of your Windows computer inside the PCem guest.

For IPX-only games, guest TCP/IP addresses are normally not required.

Hosting a game1. Start PCem Helper

Run:

pcem-helper.exe

2. Select the network mode

Choose the protocol used by the game:

TCP/IP only
IPX only
Both

Use:

• TCP/IP only for games that use IPv4 networking.
• IPX only for older IPX/SPX games.
• Both when the game or guest system may use both protocols.

3. Select the PCem connection

Choose:

Network Adapter

or:

Localhost wpcap.dll

For Network Adapter mode, select the same adapter that PCem uses.

For Localhost mode, make sure siljo-wpcap-x86.dll is next to pcem-helper.exe.

4. Select the game transport

The recommended option is:

Direct UDP

Direct UDP provides the lowest latency.

The public relay uses:

relay.siljo-planet.net
UDP port 3011

Players do not need to forward this port on their router.

WebSocket transport can be used as a fallback on networks that block UDP.

5. Enter a game name

Enter a recognizable name, for example:

Need for Speed III

or:

Duke Nukem 3D IPX

The game name may be shown on the active PCem rooms page.

6. Click Host room

The helper automatically generates a room code, for example:

AHVBRT

Send this code to the other player.

7. Start the bridge

Click:

Start Rust bridge

Wait until the helper shows:

Bridge: Running

8. Launch PCem

Use the Launch PCem button in the helper.

This is required when using Localhost wpcap.dll mode.

Start the game inside PCem and create the multiplayer session.

Joining a game1. Start PCem Helper

Run:

pcem-helper.exe

2. Use the same network mode as the host

Both players must select the same mode:

TCP/IP only
IPX only
Both

3. Select the PCem connection

Select either:

Network Adapter

or:

Localhost wpcap.dll

The connection method does not necessarily have to be identical on both computers, but using the same method makes troubleshooting easier.

4. Enter the host's room code

Enter the code provided by the host:

AHVBRT

5. Click Join room

The helper connects to the same Siljo Planet room.

Wait until the peer counter shows:

Peers: 2

6. Start the bridge

Click:

Start Rust bridge

7. Launch PCem

Use the helper's Launch PCem button when using Localhost mode.

Start the game and join the host's multiplayer session.

For TCP/IP games, enter the host guest IP when the game asks for an address:

10.77.0.62

Understanding the counters

PCem Helper displays several packet counters.

PCem TX

Packets sent by the local PCem virtual machine.

Data TX/RX

Packets sent to and received from the Internet relay.

PCem RX

Packets delivered to the local PCem virtual machine.

Dropped

Packets that could not be forwarded.

During a healthy session, you should normally see:

Dropped: 0

The counters should continue increasing while the game is using the network.

Example:

PCem TX:     1254
Data TX/RX:  1254 / 732
PCem RX:     732
Dropped:     0

Different TX and RX values are normal. Each game sends different amounts of data in each direction.

Firewall information

Allow pcem-helper.exe through Windows Firewall when prompted.

The helper needs outgoing access to:

HTTPS / WebSocket: www.siljo-planet.net
UDP: relay.siljo-planet.net:3011

Players do not need to configure router port forwarding.

On restricted school, company or public networks, direct UDP may be blocked. In that case, use the WebSocket fallback transport.

TroubleshootingThe peer counter stays at 1

Check:

• Both players entered the same room code.
• Both helpers are running.
• The room code does not contain extra spaces.
• Windows Firewall allows the helper.
• Both players selected compatible network modes.

The counter should show:

Peers: 2

before starting the game.

UDP test or bridge times out

Make sure the relay host resolves correctly:

relay.siljo-planet.net

Do not add this hostname to the Windows hosts file as:

127.0.0.1 relay.siljo-planet.net

127.0.0.1 means the current computer and would send packets to the wrong location.

Switch to WebSocket fallback when UDP is blocked by the current network.

PCem does not show the localhost adapter

Confirm that the following file exists next to the helper:

siljo-wpcap-x86.dll

Select Localhost mode and launch PCem through the helper.

The PCem adapter list should contain:

Siljo Planet Relay (localhost)

Do not manually run the DLL. A DLL is not an executable program; PCem loads it automatically.

Network Adapter mode does not capture packets

Check that:

• Npcap is installed.
• PCem and PCem Helper use the same adapter.
• PCem is configured with an NE2000-compatible card.
• The guest operating system has the correct IP configuration.
• The correct network protocol is enabled in the helper.

The game connects but has lag

Check:

Dropped
Peers
Data TX/RX
PCem RX

Use Direct UDP transport whenever possible.

For same-LAN testing, use Localhost wpcap.dll mode to avoid a second direct LAN path.

Internet latency between players and the relay server can still affect gameplay.

TCP/IP game discovery does not work

Some older games use broadcasts to find hosts.

PCem Helper forwards Ethernet broadcast, multicast, ARP and discovery traffic.

When available, try entering the host's guest IP directly:

10.77.0.60

IPX game does not connect

Confirm that both players selected:

IPX only

or:

Both

Also confirm that the same IPX frame type is configured inside both guest operating systems.

Ethernet type 0x8137 is used for IPX/SPX traffic.

Recommended configuration

For most Internet games:

PCem connection:
Network Adapter

Data transport:
Direct UDP

Network mode:
TCP/IP only

For isolated or same-LAN testing:

PCem connection:
Localhost wpcap.dll

Data transport:
Direct UDP

For older IPX games:

Network mode:
IPX only

Data transport:
Direct UDP

Active rooms

Hosted rooms may appear automatically on:

https://www.siljo-planet.net/pcem.php

The page can show:

• Game name
• Room code
• Number of players
• Network mode
• Transport type

Only room information is published. Player IP addresses and local ports are not displayed.

Getting help

When reporting a problem, include:

Game name
TCP/IP or IPX
Network Adapter or Localhost mode
Peers
PCem TX
Data TX/RX
PCem RX
Dropped
The final 20 lines of the helper log

Help and discussion

Discord