What Is Speedify’s Multi TCP and How It Works

Cristian MiculiCombining Internet Connections, Improve Internet Reliability

Multi TCP from Speedify - More Lanes for Improved Reliability

In a continuous effort to provide fast, reliable and secure Internet to everyone, here at Speedify we’re constantly improving our bonding VPN service. In this day and age when remote work, distance learning and live streaming are more important than ever, Speedify 11 has launched a new feature called “Multi TCP”. 

To put it briefly - Multi TCP in Speedify is a brand new optimized transport mode our engineers have been working on, to make the secure channel bonding / link aggregation we established years ago better. It results in better overall latency and bandwidth of the bonded connection.


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How Multi TCP Works

First of all - TCP (Transmission Control Protocol) is one of the transport protocols used in network and Internet communications. It basically divides the information being sent and received into chunks, adds a TCP header and creates a TCP segment. Then, that TCP segment is being sent over the network, following a path of “hops” until it reaches the destination - read more on how the Internet works in this article

Warning: technical details ahead!

The way Speedify works by default is it opens one TCP socket over each Internet connection it uses - e.g. one TCP socket over Wi-Fi / cellular / wired Ethernet / etc. With Multi TCP, Speedify opens up multiple sockets over each connection (for example 4) - 4 over Wi-Fi / cellular / wired Ethernet / etc.

If there’s packet loss on one of the TCP sockets, only the network packets being sent over that socket are delayed, as the TCP protocol will keep trying to send those, while the other sockets can continue sending other packets. This will minimize the negative effects of high latency and packet loss on connection performance, including the cases when you use Speedify with a single Internet connection.

In plain words

If each connection that Speedify uses were to be represented by a one lane road (e.g. Wi-Fi, cellular, Ethernet, etc.) which cars (network packets) use to get to the destination, Multi TCP adds extra lanes, so that cars are distributed over all the lanes available.

When there’s a traffic event on one of the lanes, the cars on the other lanes will keep going without being dependent on the lane that’s stuck. If that lane remains stuck, the cars that have already been sent on it will be rerouted through the other lanes.

Performance Improvements for Speedify’s Multi TCP

According to the tests we did in the Speedify Testing Lab, Multi TCP delivers most improvements for:

  • Fast connections, when a single TCP connection is not able to fully utilize those
  • Connections with packet loss - especially the wireless ones
  • Connections with high latency - e.g. satellite (including Starlink)
  • When connecting to servers located far away - e.g. remote workers using connections to other countries.

Here’s a graphic on how high speed is maintained when using Speedify’s Multi TCP transport mode vs. not using Speedify:

In the case of connecting to distant locations, we connected from Philadelphia to a server located in Singapore. While a single TCP socket connection got us around 100 Mbps in download bandwidth, when using Multi TCP, we got 200-300 Mbps.

Multi TCP - Is That Some Sort of Multipath TCP (MPTCP)?

Great question. And the answer is no. Speedify's Multi TCP works within one single connection, whereas Multipath TCP (MPTCP) works over several connections, similar to the connection aggregation / bonding that Speedify does. MPTCP is more analogous to Speedify as a whole. But here’s more below on MPTCP.

As its name suggests, Multipath TCP refers to sending the data from source to destination through multiple routes (paths). This can be done when you have multiple Internet connections available to apply MPTCP. While running, it’s creating a TCP subflow for each connection it’s putting together and sending data through different paths. 

Difference between TCP and Multipath TCP

Data is flowing through multiple flows from origin to destination. The TCP header of each segment contains, along with the source and destination IP addresses, a data sequence number, so the receiver will get the data from the multiple subflows in the original order, without any corruption. The protocol also has mechanisms to handle congestion control - what it does when one of the connections becomes slow or unreliable.

Find out more about how MPTCP works in the video below:

Speedify - How It Works and How It’s Different from MPTCP

As opposed to the limited “backup flow” ability of MPTCP, Speedify has a more complex approach to the whole thing, with advanced logic and multiple types of connection priorities. Meaning that it will use the connections being bonded according to the performance and priorities set by the user. Speedify will send as much data as it can on:

  • non-metered connections, such as wired Ethernet and Wi-Fi, before sending a lot of data through cellular
  • lower latency connections, such as wired (cable, DSL), before wireless (cellular, satellite)
  • higher bandwidth connections before slower ones.

Imagine Speedify as an on-call optimization specialist, monitoring the quality of each connection at any time and deciding how much data to send over each one so the overall Internet connectivity is at its best. Plus - it’s all encrypted, so nobody can sniff your Internet traffic.

Here’s a comparison table between MPTCP and Speedify:


Multipath TCP (MPTCP)


Allows the use of all available connections



Failover protection



Error correction and packet loss



Software-only solution implementation

Linux, MacOS 10.10+

Linux, MacOS, Windows, iOS, Android

Communication security (encryption)

When running secure protocols over MPTCP (i.e. HTTPS)


Able to dynamically use other protocols (i.e. UDP)



Connection priority



Cost aware



Maximizes bandwidth

yes, limited to the implementation logic


Solution cost

depends on type of implementation (dedicated hardware / software-only) and support needed to set up and maintain

as low as $3 / month

As you can see, there’s a lot that Speedify has to offer when compared to the existing MPTCP implementations. Make sure to give Speedify a try!

Use all of your connections at the same time

Multiple connections, maximum performance

Speedify can bond any combination of 2 or more Internet connections and will intelligently distribute your online traffic between them for optimal performance.

In the majority of cases, Speedify will automatically detect and start using any Internet connections available to your device - but if you need help we have quick start guides available for most common set ups.

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How Speedify Helps You Get Faster, More Reliable Internet

Everything that uses slow, unreliable and wireless Internet connections are the prime beneficiaries of Speedify - from RV travelers and commuters to remote workers and live streamers. Why? Because it caters to their problems and offers an elegant solution. 

Inherently wireless connections such as Wi-Fi, mobile data and satellite are prone to coverage issues and high latency. When you are far from the hotspot or cellular tower, the connection is slow and has added lag. Plus, when your device does the handover from Wi-Fi to cellular or between Wi-Fi networks, an Internet drop is expected, while the new connection is established. This affects especially bandwidth-intensive applications, such as live streaming (including video calls) and gaming. 

By using all your available connections at once, you are safe from such issues. The apps you’re running won’t even see that something’s up, because Speedify will automatically adjust the data rate it’s sending through each connection.

If you’re not yet familiar with Speedify, learn more by visiting our website. To get started, get Speedify now!


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