Occurs both on 2.4Ghz and 5Ghz network. Already confirmed it's not an issue from the wifi router since all other devices (phones, Surface Pro 3) do not experience this issue.
So, the original poster had an older router that didn't even support 802.11ac. And I think that while your other devices connect and maintain connections without any issues, none of them have the newest 802.11ax (WiFi 6). Older routers are not always forward compatible with newer standards. -
From personal experience - I've got a ton of devices. SP3/SP5, iPhone XS, iPad Air, tons of smart home devices and so on. My new SP7+ (has the same Intel 201AX as the SP7) had issues with a fairly recent 802.11ac dual band router. My older devices (some of them, not all, and I have yet to analyze which chipsets had connectivity issues) had some issues with a new 802.11ax router (which probably will get resolved down the road with firmware updates for the 802.11ax router for backwards compatibility). So, I took my newer 802.11ax router and changed it to access point mode and plugged in into the older router so that the older router continued to be the edge device and handle DHCP, etc. Then, I connected the SP7+ to the AX WiFi and left the others on the older 802.11ac wifi. All devices are very happy.
TLDR; bottom line is that some older routers before the launch of the 802.11ax
standard may have issues with WiFi 6 devices.