I`m having the exact same issue. Does anyone have a fix or workaround?
Same problem encountered in my nokia 8. Is it anyway related to H/w? My phone is relatively new, came with Android 7, but I upgraded to 8 and 8.1 within day and a month of purchase.
Not sure it is anything to do with router as my Samsung Note 4 is working without issues while connected to the same router. Google for this issue brings up stories from of folks who have encountered similar issues in Oreo 8.1 on Google phones. Could be firmware related or Oreo 8.1 related.