2.4GHz wifi gets unusable when I use Bluetooth. I had no problems with my Samsung S6 edge.
There is about 15megabit download, takes forever to test (speedtest) jitter and ping is through the roof, the response is very bad when opening webpages and using programs that use internet.
I have tried changing channel.
On 5GHz it works very well and it seems like it is no problems on response nor speed, except that the Nokia has terrible reception regardless of wifi band.
I would guess the phone uses same antenna for the wifi and Bluetooth, I would have expected the Qualcomm chip would handle it... I haven't read the specs on the chip or it's amplifiers.