I would love to have something like this. When I call an Uber/Lyft as I am walking out of my apartment, it always takes forever for the WiFi to disconnect, long after it has lost internet connection. So I constantly get the "Unable to Connect to Network" error, and I have to turn off WiFi and restart the app to actually call a ride.
If anyone knows of a solution to this problem on a Galaxy S8 I would love to hear it.
What you're experiencing is different. The WiFi still has internet access, your signals aren't reaching the AP. The phone has no way of remedying this without switching to LTE very aggressively. I'd assume that would cause unnecessary battery drain and unneeded switches for many people.
That said, I haven't needed to restart the uber app to fix this. I just disable WiFi from the notification toggle and the app connects in about a second after that.
If anyone knows of a solution to this problem on a Galaxy S8 I would love to hear it.