FFS.............
I'd been struggling with one laptop doing this for weeks. Customer kept calling me back time and time again. In the end I fixed it by downloading the latest wireless drivers from the laptop supplier (the Win10 automatic upgrade had installed a different set, while the default Broadcom drivers were also bad) and also set the router to give a fixed DHCP address for this one machine.
I couldn't give it a fixed IP address because it was used on other networks - where it behaved.
It appeared to be a combination of the default Microsoft wireless drivers for Broadcom chipsets and the BT Homehub