A recent Sprint firmware update has boosted download speeds on the Samsung Galaxy S8 by at least 20 percent, according to Sprint execs and exclusive data PCMag collected from Ookla's Speedtest Intelligence.

The news shows why it's always important to accept those carrier firmware updates that force you to reboot your phone. In Sprint's case, a bug in the Qualcomm Snapdragon 835 radio code was causing Galaxy S8 phones to drop off Sprint's premiere Band 41 LTE network sooner than they should have, falling back to the slower bands 25 and 26.

"There was a miscalculation in the software that was reading the device, so it tuned away from Band 41 before it should," said Ryan Sullivan, VP of product engineering and development at Sprint. "Working back with Qualcomm and Samsung, we quickly found it, diagnosed it, and launched the update on June 5."

Both owners of Sprint-branded and unlocked Galaxy S8 phones are getting the update, Sullivan said. About 85 percent of Sprint's Galaxy S8 owners have already upgraded.

We compared speeds on the Galaxy S8, Galaxy S7, Galaxy S6, iPhone 7 and iPhone 6 series (including their Plus phones) during May 1-7 and July 1-7. While speeds on all of the other devices remained about the same, Galaxy S8 average LTE download speeds jumped by 20 percent from 21.9Mbps to 26.4Mbps. The update didn't affect upload speeds.

Sprint provided us with some internal studies, based on the same data set but somewhat different timing (April 24 versus June 26) and slightly different methodology, which showed an even better improvement, from 21.6Mbps to 28.9Mbps. In any case, there's been a considerable boost based on the new firmware.

The changes also affected HTC U11 phones on the Sprint network, which in ideal conditions, should be even faster than Samsung Galaxy devices because they support 4x4 MIMO antennas on Sprint's fast Band 41 system. Between May 28 and July 8, we saw a huge jump in download speeds on U11 devices, from an average of 19.2Mbps to 27.9Mbps.

There's still one slight mystery: according to Ookla's data, Samsung Galaxy S7 phones on Sprint are faster than both of the newer devices, hovering around 30Mbps. That may be because not all Galaxy S8 owners have installed the new firmware.

Sprint argues that the Galaxy S8 upgrades have moved it from fourth to third place on speed for Galaxy S8 owners, putting it slightly ahead of Verizon on Galaxy S8 download speeds. Our analysis of Ookla data puts Sprint slightly behind Verizon during the first week of July, with Verizon at 27.4Mbps down to Sprint's 26.4Mbps—but the point is, they're close.

This is important to Sprint because the company has been strenuously trying to reverse its reputation for poor network performance. According to Speedtest Intelligence, Sprint is still in fourth place among the major carriers on download speeds, but the gap has been closing over the past year: while there was about a 5Mbps difference between the fourth- and third-place networks in June 2016, it's down to about 3Mbps in June 2017.

(Our Fastest Mobile Networks study, which Verizon won nationwide, uses a complex Speed Score metric factoring in download speeds, upload speeds, latency, and network reliability. It was based on tests run in May, so it doesn't reflect improvements made in June.)

Moving Targets, Continual Improvements

Sprint's device upgrades also go with network upgrades. Network performance is a moving target; this summer, for example, Sprint is increasing its rollout of gigabit LTE in cities like New Orleans and deploying "magic box" indoor coverage devices to improve Band 41 signal in residential areas.

Just today, AT&T announced its misleadingly named "5G Evolution" launch in Indianapolis—that's its own version of gigabit LTE. That only works with Galaxy S8 and S8+ phones for now, although it will work with other devices in the future.

The takeaway here is that your phone matters when it comes to network performance; the Galaxy S8 is really good; and you should update your firmware. Sprint users, especially, will see a big boost from keeping on the latest software at all times.

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