Qualcomm vs. Broadcom
When we look at the results of the individual devices from the test field, we see two things that stand out. First of all, there are considerable differences between the highest speeds achieved in combination with the R7800 (Qualcomm chip) and the R8000 (Broadcom chip).
With the R8000, only the Samsung Galaxy S8 on the 5 GHz band is able to tap the 400 Mbit/s limit, followed by the iPhone 7 (375 Mbit/s) and the HTC U 11 (351 Mbit/s). On the R7800, in addition to the S8 (403 Mbit/s), the OnePlus 5 (430 Mbit/s) and the U 11 (447 Mbit/s) manage to exceed this limit.
On the 2.4 GHz band, the differences are still noticeable, but much smaller. In combination with the R7800, it is the S8 with 105 Mbit/s and the U 11 with 103 Mbit/s that lead the list, followed by the OnePlus 5 with 96 Mbit/s. Together with the R8000, the S8 again outperforms the competition with 90 Mbit/s, this time flanked by the Huawei's P10 Plus with also 90 Mbit/s. Huawei's P10 takes third place at a measured speed of 88 Mbit/s.
At the top of the curve, in combination with a Qualcomm chip-based router, the phones are able to reach significantly higher speeds, particularly at 5 GHz. At the lower point it is clear too see that the phones perform much worse paired with the R7800 on the 5 GHz. At the bottom of the list we find the Huawei P10 and P10 Plus with respectively 66 and 73 Mbit/s and the Motorola Moto Z2 Play with 117 Mbit/s. With the R8000, only the Z2 Play is out of line with 107 Mbit/s, the Samsung Galaxy A5 (2017) and LG's G6 reach speeds of 167 and 175 Mbit/s respectively).
On the 2.4 GHz band, the differences are much more levelled out. With the R7800, it's the Sony Xperia X Compact (41 Mbit/s), Z2 Play (42 Mbit/s) and ASUS Zenfone AR and BlackBerry's KeyOne (both 45 Mbit/s) that are at the bottom of the list. With the R8000, the Honor 8 (34 Mbit/s), General Mobile GM5 Plus and again the KeyOne (both 40 Mbit/s) perform the lowest.
In any case, the differences in absolute terms between the top and bottom of the ranking are enormous. On the 5 GHz band, the difference between the best performing smartphone and the least impressive device in combination with the R8000 is already a massive 293 Mbit/s, while the difference on the R7800 increases to 381 Mbit/s! A difference of a factor of 4 and a factor of 7 respectively is enormous and therefore certainly a consideration when selecting a new device.
At 2.4 GHz, the differences are smaller - 64 Mbit/s or factor 2.5 on the R7800 compared to 56 Mbit/s or factor 3 on the R8000 - but still significant. We can only conclude that there is a world of difference in the quality of the WiFi implementation. This makes it all the more regrettable that we cannot determine to an individual chip level which chips have been used by the various manufacturers, although the antennae orientation chosen will certainly also be a factor.
There does not seem to be an overarching correlation between a particular SoC manufacturer, router chipset vendor and performance. For example, we see SoCs from Qualcomm, HiSillicon and Exynos at the top and bottom of the list. At the top, we'll also find Apple's two chips - given the pricing of the iPhone's we would expect them to be - and we'll find the Mediateks alternating between the middle and bottom of the list.
The S8 is by and large the best performing smartphone in terms of Wi-Fi speed, followed at some distance by the iPhone 8 Plus, HTC U 11, OnePlus 5 and iPhone 7. Given the pricing and positioning of these devices, this is hardly surprising. On the other hand, you also have devices with similar pricing such as the ASUS ZenFone AR (average 949 euros) and the BlackBerry KeyOne (average 599 euros) that score well below expectations, especially at 2.4 GHz.
Sony's XZs (average 599 euros) and XZ Premium (average 732 euros) also lag somewhat behind the expectations you can have with a phone in such a price range. The same applies to the Huawei P10 (average 538 euros) and P10 Plus (average 745 euros), which perform less well especially when combined with the R7800.