WiFi going offline?

Hi all, has anyone experience wifi going unavailable after some period of uptime of the phone (FP5)? I have noticed on a couple of occasions now that WiFi seems to stop working, where the phone would have been connected to a network and then the wifi icon vanishes, and going into the wifi networks list, it shows nothing. Toggling wifi or putting the phone into airplane mode does not resolve the issue. I have to restart the entire device for it to then sort out.

Any ideas?