SpeedFusion Boost is a new checkbox in Peplink firmware 8.6 that changes how TCP behaves inside a SpeedFusion tunnel. Normal TCP sees a lost packet and assumes the network is congested, so it cuts its sending rate and slowly climbs back up. On cellular and Starlink, most of that loss comes from the radio link, not from congestion, so TCP slows itself down for no good reason. SpeedFusion already measures every link in the tunnel and handles loss on its own. Boost lets a TCP session take advantage of that instead of second-guessing it.
We set it up on a MAX BR2 Pro in our lab two ways: through InControl 2, and locally in each device's web admin. Then we ran ten tunnel tests on a single T-Mobile cellular link, five with Boost off and five with it on. Every screen and every result is below.
What SpeedFusion Boost does
TCP congestion control was designed for wired networks, where a dropped packet almost always means a router somewhere is overloaded. The sender's congestion window (cwnd) is how much data it lets itself have in flight before it waits for acknowledgments. When a packet goes missing, TCP shrinks that window, often by half or more, and then grows it back over several round trips.
Cellular and satellite links drop packets for other reasons. Signal fades, tower handoffs, and Starlink switching satellites all cause short bursts of loss and latency spikes. TCP can't tell the difference, so a 5G or Starlink connection with plenty of capacity ends up with single downloads that sawtooth up and down well below what the link can carry.
A SpeedFusion tunnel already knows what each WAN is doing. Dynamic Weighted Bonding tracks latency and loss per link, retransmits inside the tunnel, and shifts traffic between WANs. With Boost on, TCP sessions in the tunnel stop reacting to every lost packet as if the network were full. Peplink's help text in the web admin says it "helps improve throughput when the connection suffers from packet loss and high latency." In our tests, the congestion window stayed large with Boost on through retransmits that cut it down with Boost off.
A note on how Boost works: At the time of writing, Peplink hasn't published official notes on what Boost changes under the hood. Its firmware 8.6.0 page describes Boost only at a high level, as keeping unstable links from pulling down a bonded tunnel. The congestion explanation in this post is what we believe is happening, based on our years of network engineering and on what our lab tests show. It behaves like a loss-tolerant congestion control that reacts to measured bandwidth and delay instead of to every lost packet. We'll update this post if Peplink publishes more detail.
What you need
- Firmware 8.6.0 or newer on both ends of the tunnel. Our BR2 Pro ran 8.6.1 and our hub ran 8.6.0. Some models, including the BR2 Pro, have to step through 8.5.4 first. Our firmware 8.6.1 update guide covers the upgrade.
- A SpeedFusion peer. That can be a FusionHub, a Balance router at your office, or another Peplink or Pepwave router. Our lab hub is a FusionHub virtual appliance running in a cloud data center.
- Traffic that goes through the tunnel. Boost only affects traffic inside SpeedFusion. If your clients go straight out the WAN, Boost does nothing for them. Use Send All Traffic To or an outbound policy rule to route the traffic you care about through the tunnel.
- TCP traffic. Boost works on TCP. UDP traffic, which includes most voice and video calls, goes through the tunnel the same as before.
Boost is still labeled beta, even on firmware 8.6.1. The help text on our 8.6.1 BR2 Pro says so, and the 8.6.1 release notes list Boost fixes without dropping the label. It's off by default on every profile, new or existing.
Our lab setup
- Peplink MAX BR2 Pro, firmware 8.6.1, one T-Mobile SIM in Cellular 1 on LTE-A. Both Ethernet WANs were unplugged, so every test ran over cellular.
- FusionHub, firmware 8.6.0, hosted in the cloud.
- SpeedFusion profile using Dynamic Weighted Bonding with default settings: no WAN Smoothing, no Forward Error Correction, and no TCP Ramp Up.
Option 1: Set up SpeedFusion with Boost in InControl 2
If both devices are in the same InControl 2 group, this is the easiest way. InControl 2 builds the profile on both ends and pushes it to the devices for you.
Step 1: Turn on SpeedFusion VPN for the group
In InControl 2, open the group and go to SpeedFusion VPN > Configuration. Check Enabled, then click Add Profile.
Step 2: Pick a topology
Choose Star for a hub and its remote routers. That's the right choice for one hub and any number of field routers. Fully Meshed connects every device to every other device, and Point-To-Point links exactly two.
Step 3: Choose the hub
Select your hub from the Device list. InControl 2 fills in the hub's public IP address. We blurred ours.
Step 4: Choose the endpoints
Check each router that should connect to the hub. We picked our BR2 Pro.
Step 5: Name the profile and check SpeedFusion Boost
Give the profile a name. Boost isn't on the default screen. Check Show advanced settings at the bottom left of the window, then check SpeedFusion Boost. Leave the rest at the defaults unless you have a reason to change them. Click Next, then Finish.
We ran our baseline tests first with Boost unchecked, then came back to this screen with Edit and checked it. That's all it takes to try Boost on a tunnel you already have.
Step 6: Save Changes
Click Save Changes at the bottom of the page. InControl 2 pushes the profile to both devices, usually within a minute. You can watch for "PepVPN configuration has been updated by InControl" in the group's event log.
Option 2: Set up SpeedFusion with Boost locally, without InControl 2
You can build the same tunnel in each device's web admin. You set it up twice, once on the hub and once on the remote router, and each side needs the other's Local ID.
If InControl 2 already manages SpeedFusion on these devices, disable that profile in InControl 2 first. Unchecking SpeedFusion for the whole group did not remove the profile from our devices. Clicking Disable on the profile itself and saving did.
Step 1: Find each device's Local ID
On each device, go to Advanced > SpeedFusion VPN. The SpeedFusion VPN Local ID box shows the name the other side will use as its Remote ID. Write down both.
Step 2: Create the profile on the hub
On the hub, click New Profile and fill in:
- Name: anything that tells you which router it's for.
- Remote ID: the remote router's Local ID.
- Pre-shared Key: a long random key. Use the same key on the router. Our lab screenshots show this field blank, so don't copy that part.
- Remote IP Address / Host Names: leave blank on the hub. The router will connect to the hub, not the other way around.
- SpeedFusion Boost: checked.
Click Save, then Apply Changes at the top of the page.
Step 3: Create the profile on the remote router
On the BR2 Pro, click New Profile and fill in:
- Name: the hub's name works well.
- Remote ID: the hub's Local ID.
- Pre-shared Key: the same key you used on the hub.
- Remote IP Address / Host Names: the hub's public IP address or hostname.
- SpeedFusion Boost: checked.
Click Save, then Apply Changes. Lower on the same page, WAN Connection Priority controls which WANs the tunnel uses. The default puts every WAN at priority 1, so the tunnel bonds all of them.
Step 4: Confirm the tunnel is up
Go to Status > SpeedFusion VPN. The hub should show a lock icon with a tunnel address, and each WAN in the tunnel shows Rx, Tx, loss, and latency once traffic flows.
How we tested
Peplink routers have a throughput test built into the SpeedFusion status page. Click the arrow at the right end of the peer's row to open the details window, then scroll down to SpeedFusion VPN Test Configuration. We used:
- Type: TCP
- Streams: 1
- Direction: Download
- Duration: 20 seconds
We used one stream on purpose. Most speed test sites open several TCP connections at once, which hides how a single connection behaves. A single stream is a file download, a backup upload, or a video stream, and it's where TCP backoff hurts the most.
The test reports throughput, retransmits, and the congestion window every second. The congestion window column shows whether TCP is backing off.
Results: Boost off vs Boost on
Cellular throughput changes minute to minute, so one test of each tells you almost nothing. We ran five with Boost off and five with Boost on. Three of the Boost-on runs used the InControl 2 profile and two used the local profile. We went back to Boost off at the end to make sure the signal hadn't just improved over time.
| Run | Boost off | Boost on |
|---|---|---|
| 1 | 14.6 Mbps | 53.0 Mbps |
| 2 | 38.1 Mbps | 55.3 Mbps |
| 3 | 51.6 Mbps | 42.8 Mbps |
| 4 | 57.4 Mbps | 35.6 Mbps |
| 5 | 31.7 Mbps | 48.5 Mbps |
| Average | 38.7 Mbps | 47.0 Mbps |
Boost on averaged 47.0 Mbps against 38.7 Mbps with it off, about 21% higher. The fastest single run was a Boost-off run at 57.4 Mbps. What changed more was the bottom of the range. With Boost off, our slowest run fell to 14.6 Mbps. With Boost on, the slowest was 35.6 Mbps. Boost didn't raise the ceiling of our cellular link. It kept single downloads from collapsing when the link got noisy.
What the congestion window shows
Here's our slowest Boost-off run. The window grew to 601 KB, then 11 packets were retransmitted at the 8-second mark. Over the next few seconds TCP cut the window back to about 104 KB and never recovered, and the run finished at 14.6 Mbps.
Now a Boost-on run on the same link a few minutes later. It had 83 retransmits, far more than the run above, yet the window stayed near or above 1 MB for most of the test. It dropped once, to 141 KB at the 18-second mark, and was back above 1.3 MB a second later. It finished at 53.0 Mbps.
The loss still happened in both runs. With Boost on, SpeedFusion handled it inside the tunnel and the TCP session kept its window open.
What about Starlink and 5G?
Our test used one LTE-A connection. The same problem shows up on Starlink and 5G, often worse. Starlink switches satellites every 15 seconds, and latency jumps during each switch. 5G throughput swings with signal and load. Both produce the kind of short loss and latency spikes that make normal TCP back off when it doesn't need to. If you run SpeedFusion over either one, Boost is worth a test. Run the same single-stream tunnel test a few times with it off and a few times with it on, and compare the averages and the lowest runs, not just one result.
Things to know before you turn it on
- It's beta. Peplink still labels Boost as beta on firmware 8.6.1 and says results may vary. 8.6.1 also fixed a bug where Boost could drop traffic on certain ports, so update both ends before you test. Try it on one profile before you roll it out to a fleet.
- Turn it on at both ends. In InControl 2 it's one checkbox on the profile. Locally, check it on the hub's profile and on the router's profile.
- Watch for devices that stop connecting. One Peplink forum user reported that a weather station stopped reaching its cloud service after Boost was enabled. If a device misbehaves, route that device's traffic outside the tunnel with an outbound policy rule, or turn Boost off on that profile.
- It isn't WAN Smoothing. WAN Smoothing sends duplicate packets across links to hide loss, at the cost of extra data. Boost doesn't duplicate anything, so it doesn't add data usage. You can use both on the same profile.
- TCP Ramp Up is a separate setting. It's the checkbox right above Boost in the profile. We left it off for all of our tests so the results show Boost alone.
Common questions
Where is the SpeedFusion Boost setting?
In InControl 2, it's in the SpeedFusion profile options after you check Show advanced settings. In the local web admin, it's in each profile under Advanced > SpeedFusion VPN, just below Bandwidth Limit.
Does SpeedFusion Boost cost anything?
No. It's a checkbox in firmware 8.6. You still need a SpeedFusion peer, which may have its own license, like FusionHub or SpeedFusion Connect.
Does Boost help regular internet traffic?
Only traffic that goes through the SpeedFusion tunnel. Traffic that leaves straight from a WAN is unchanged.
Does Boost help video calls?
Not directly. Most voice and video apps use UDP. For calls, WAN Smoothing and Hot Failover are the SpeedFusion features that help.
Should I turn it on for every profile?
For tunnels over cellular or Starlink, it's worth testing. Peplink plans to make Boost the default in a later firmware release. Until it leaves beta, enable it on one profile at a time and check your traffic.
Shopping for a router? See the Peplink routers we stock and why we recommend Peplink.
Need help setting it up?
Our network engineers set up SpeedFusion on Peplink and Pepwave routers every day. Call or text 888-381-7750, Monday through Friday, 6:30 AM to 3:00 PM Pacific.
Sources: Peplink Firmware 8.6.0, Peplink firmware 8.6.1 release notes, the built-in help text in InControl 2 and on a MAX BR2 Pro running firmware 8.6.1, and our own lab tests on October 20, 2026.
