Sending Multi-GB Files: What Breaks and How to Prevent It

October 8, 2026

A 20 MB photo either arrives or it does not, and you find out in seconds. A 6 GB video is different. It runs for ten minutes or an hour, and every small interruption that would never matter for a short transfer now has time to happen. Almost every failed multi-gigabyte transfer comes down to one of a few causes, and each of them is easy to prevent once you know what to look for. This guide walks through them in the order they usually bite.

Your device falls asleep halfway through

The most common cause by far. A phone locks its screen after a minute or two, a laptop dims and then sleeps, and the browser tab that was streaming your file gets paused or throttled. The transfer does not so much fail as stall, and it often looks like it is stuck at some random percentage. The fix is boring and reliable: keep the screen on and the device plugged in for the whole transfer. Nearsend asks the browser to keep the screen awake while a transfer is running, where the browser allows it, but the browser can refuse, so treat that as a safety net and not a promise. On a laptop, check that the lid will not close and the power plan will not put it to sleep in the next half hour.

The receiving browser has to hold the file

Browsers cannot stream an incoming file straight to your disk the way a download manager can. In Nearsend the receiving browser collects the pieces in memory and writes the finished file out when you save it. That works well up to a point, and it is the reason very large files are best received on a computer, not a phone with limited memory. Nearsend sets no size cap of its own, but it will warn you before you accept a very large transfer: at 1 GB on a computer and at 500 MB on a phone. If you see that warning on a phone, consider receiving on a laptop instead, and close other heavy tabs before you accept.

Weak Wi-Fi: the slowest link sets the speed

A transfer between two devices is only as fast as the slower of their two connections. Two laptops on a strong 5 GHz network can move a gigabyte in well under a minute. A phone at the far end of the house on a crowded 2.4 GHz band can take ten times as long, and is far more likely to drop. If a big transfer matters, move both devices closer to the router, switch the phone to the 5 GHz network if you have one, and pause other heavy use such as video calls or cloud backups while you send.

When the connection goes through a relay

Most of the time two devices connect directly. Some networks, including certain corporate and mobile networks, block direct connections, and the transfer then goes through an encrypted relay server instead. The data is still encrypted end to end, but the relay adds distance and shares bandwidth, so large files move more slowly. Nearsend shows whether the current connection is direct or relayed. If you see relayed on a very large transfer, moving both devices to the same ordinary home or office Wi-Fi often brings you back to a direct path.

Phones: background tabs, battery and mobile data

Mobile browsers aggressively pause tabs that are not on screen. If you switch apps to reply to a message while a large file is sending, the transfer may slow to a crawl or stop. Stay on the Nearsend tab until it finishes. Low battery modes can also reduce background activity, so charge first. And if the phone is on mobile data instead of Wi-Fi, remember that a 4 GB transfer will use 4 GB of your plan, which is worth a thought before you start.

What a dropped link does to your transfer

Brief drops are normal, especially on Wi-Fi that hands off between access points. Nearsend waits a few seconds before treating a drop as real, and tries to bring the connection back automatically. If it cannot, files that already finished stay finished, and any file that failed part-way can be retried from the same screen, so you do not have to start a whole folder again for one bad file. That is another argument for sending a big collection as a folder or batch, not as one giant archive.

A short pre-flight list

Before a big send: plug in both devices, turn off auto-sleep for now, put both on the best Wi-Fi available, close heavy tabs on the receiver, decide which device will receive (a computer if you can), and keep the Nearsend tab in front until the completion message appears. Five minutes of preparation is cheaper than restarting a transfer that was already ninety percent done.

When a different tool is the better choice

Direct transfer needs both devices online at the same time, because the file never waits on a server. If the other person is asleep, in another time zone, or will not be at their computer for hours, a link-based cloud service is the more practical tool, even though it means uploading first. Use direct transfer when you are both there and want the file moved now, privately, with nothing stored afterwards.