Network Emulation
Explained

01Main Network Emulation Functions

Each module targets one property of a network path. They can run alone or stacked, and each can be applied to outgoing traffic, incoming traffic, or both directions.

Latency

Latency adds a delay to packets before they are passed on. You can set a fixed delay or a range.

• If you process traffic in both directions, the delay is applied twice on a duplex connection: once when your packet goes out, and again when the reply comes back in. A 100 ms setting in both directions adds roughly 200 ms to your round trip.
• The difference between Delay from and Delay to defines jitter, the variation in delay from packet to packet. The wider the range, the more erratic the timing. Set both values the same for a steady, constant delay.
• Latency directly raises your ping. Jitter is often more disruptive than raw latency, because applications struggle to predict arrival times.

Packet Loss

Packet loss drops a percentage of packets so they never arrive. Packets are discarded at the point they are received or sent out, depending on direction.

FR05T can simulate both individual and sequential (burst) loss:

• With a range set, the emulator randomly generates loss runs between the minimum and maximum lengths.
• Burst loss is far more realistic than random single-packet loss, since real congestion and wireless interference tend to drop packets in clusters.

Duplication

Duplication sends a copy of selected packets, so the same packet arrives twice. The duplicate is sent either to the remote computer or to your local TCP/IP stack, depending on direction.

• Well-behaved protocols detect and discard duplicates, so the visible effect is usually extra bandwidth use rather than errors.
• Poorly written applications may process the duplicate as new data, which is exactly what this module lets you observe.

Reordering

Reordering delivers a percentage of packets out of sequence. The emulator pulls a packet out of the flow, lets the number of packets specified as the Gap pass normally, then re-inserts the held packet.

• A larger Gap holds the packet longer, producing more severe reordering.
• Real-time applications over UDP are especially sensitive here, since a late packet often has to be discarded entirely.

Corruption

Corruption flips a random bit inside a packet to simulate a transmission error or a faulty network device. There are three ways to specify how often it happens:

Port Blocking

Port blocking drops all packets to and from the ports you list. This simulates a firewall, or the situation where an ISP filters certain traffic.

• List individual ports or ranges, separated by commas.
• Prefix a port with T for TCP only or U for UDP only. No prefix blocks both.

Bandwidth Limiting

Not part of the original module list, but closely related: FR05T's Bandwidth Manager caps throughput per direction, from a few bits per second up to gigabit speeds. This lets you observe how an application behaves on a slow or congested link without touching any other property.

• Combine a low bandwidth cap with moderate latency to simulate a realistic mobile or rural connection.
• Advanced mode lets you build named rules that target specific IPs or CIDR ranges with priority ordering.

02Requirements

• A PC running Windows 7 or higher. Windows 10 or 11 is recommended for the most reliable hotspot support.
• To emulate traffic for a console or second device, that device's traffic must pass through your PC. You share your PC's connection either with an Ethernet cable from PC to console, or by creating a virtual hotspot the console connects to.
• Network emulation affects peer-to-peer and server-relay connections, where traffic between players flows through the path you control.
• It has no effect on dedicated-server games. When every player connects directly to a central server, altering your own path only affects your own connection to that server.

03Sharing Your Connection

Two approaches. Ethernet is more stable and lower latency; a hotspot is more convenient. FR05T's built-in Hotspot & Sharing tool automates both, but here is what is happening underneath.

Option A: Ethernet cable

Option B: Windows Mobile Hotspot

04Video Walkthrough

A step-by-step video showing how to share your PC's connection to a console for testing.

05Finding Your Best Settings

There is no universal "best" configuration. Results depend on:

Because all of these differ from setup to setup, nobody can hand you accurate settings. Values that work perfectly on one machine can disconnect another. The only reliable method is to test on your own setup.

A testing method that works

06Troubleshooting

• Nothing is being affected. Check that you selected the adapter facing the console, not your internet adapter. Confirm traffic is actually flowing through the PC by watching the Session Sniffer.
• The emulator will not start. Run FR05T as administrator. The WinDivert driver needs elevated permissions to hook the network stack. Some antivirus tools block driver installation; add an exception if prompted.
• Console has no internet after sharing. Make sure the console is set to automatic IP and DNS, and that the correct adapter is selected under the Sharing tab. Disable and re-enable sharing if it was set up before the cable was connected.
• Hotspot keeps dropping. Use the 5 GHz band, keep the console close to the PC, and make sure Windows is not putting the Wi-Fi adapter to sleep (Device Manager → adapter → Power Management).
• Constant disconnects even at low values. The application probably has a strict timeout. Reduce the value, shorten the duration, or try emulating one direction only.
• High ping before emulation starts. That is your baseline connection or hotspot overhead. Fix the underlying network first; emulation adds on top of whatever is already there.

07Glossary

Ping

The round-trip time for a packet to reach a destination and return, measured in milliseconds.

Latency

The one-way delay for a packet to travel from sender to receiver. Two latencies make up one ping.

Jitter

Variation in latency from packet to packet. High jitter makes arrival times unpredictable.

Packet

A small chunk of data with addressing information. All network traffic is broken into packets.

TCP

A protocol that guarantees delivery and order by retransmitting lost packets. Used for web pages, downloads, and most reliable transfers.

UDP

A protocol with no delivery guarantee. Fast and lightweight, used by most real-time applications, voice, and games.

P2P (peer-to-peer)

A connection model where participants exchange data directly with each other rather than through a central server.

Server-relay

Participants connect to each other through a relay that forwards traffic, but the connection between peers still passes through paths each participant can influence.

Dedicated server

Every participant connects to one central server that runs the session. Altering your own path only affects you.

Duplex

Two-way communication. Emulating both directions means each setting is applied on the way out and again on the way back.

ICS (Internet Connection Sharing)

The Windows feature that lets one PC share its internet connection with other devices.

WinDivert

The packet capture and injection driver FR05T uses to intercept and modify traffic on Windows.