Why Is My File Transfer Slow? A Checklist That Actually Helps

A slow transfer usually has one boring cause, not five mysterious ones. Here’s the order we’d go through it if you sent us a “this is crawling” message. Start at the top. Most people find the culprit in the first three.

1. Check the sender’s upload speed

Run a speed test on the sending device and look at the upload number. If it says 15 Mbps, the transfer will never go faster than about 2 MB/s, no matter what anything else does. If that’s your situation, the upload speed post explains the maths. Not much else on this list will help.

If the upload is fine, keep going.

2. Get off 2.4 GHz Wi-Fi

Most routers broadcast two networks: 2.4 GHz and 5 GHz (newer ones add 6 GHz). Sometimes they share one name and your device picks for you.

• 2.4 GHz reaches further but is slow and crowded. Neighbours’ routers, Bluetooth and even microwaves all use it.
• 5 GHz is much faster but doesn’t go through walls as well.

If you’re in the same room as the router, or one wall away, 5 GHz will almost always win. On a laptop, check which band you’re on in the Wi-Fi details. If your router lets you split the names (for example Home and Home-5G), join the 5 GHz one.

3. Try a cable

Honestly, this fixes more slow transfers than anything else. A ten-year-old Ethernet cable will usually beat good Wi-Fi for a long transfer, because it doesn’t drop speed when someone walks between you and the router. If you’re sending something big and can plug in, plug in.

4. Turn off the VPN (for this transfer)

VPNs add a detour. Your traffic goes to the VPN server first, often in another country, then on to its destination. That costs speed, and some VPNs cap bandwidth or block the peer-to-peer connections that direct transfers use.

BoltShare connections are already encrypted in transit, so you’re not giving up protection for the file itself by pausing the VPN for the transfer. Switch it back on afterwards if you use it for other reasons.

5. Stop everything else that’s uploading

Cloud backups are the sneaky one. iCloud Photos, Google Photos, OneDrive, Dropbox and Backblaze can quietly use most of your upload while you’re trying to send something. So can a video call on another device in the house. Pause them for the duration.

6. Keep the tab in front (especially on phones)

Browsers save battery by slowing down tabs you’re not looking at. On a desktop, a background transfer usually keeps going fine. On phones, it’s a different story. Switch to another app or lock the screen, and the browser may pause the page entirely. We wrote a whole post about keeping transfers alive on phones and laptops.

7. Try the other transfer mode

BoltShare has two modes: Direct P2P and Bolt Tunnel. Which one is faster depends on the networks involved:

• If you’re both on the same local network, Direct P2P can be extremely fast because the data may never leave the building.
• If you’re far apart, or one of you is on a restrictive network, Direct P2P may end up routed through a relay anyway, and Bolt Tunnel can be faster and steadier.

If one mode is crawling, start the transfer again with the other. It takes thirty seconds to test. This post explains the difference between the two modes.

8. Check the receiver’s side too

Less common, but it happens:

• The receiver’s disk is nearly full, or it’s a slow USB stick, so writes can’t keep up.
• The receiver’s device is old and struggling (lots of tabs open, low memory).
• The receiver is on hotel or café Wi-Fi with a shared, throttled connection.

9. Restart the router

It’s a cliché because it works. Routers that have been up for months sometimes get into a bad state. Unplug it for 30 seconds, plug it back in, give it two minutes, and try again.

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If you’ve been through all of this and it’s still slow, tell us about it. Include both devices, both browsers, roughly where each person is, and which mode you used. That’s usually enough for us to spot what’s going on.