I have tried performing a completely fresh install of the latest version of octoprint with no change in behaviour. Checked SSID and password are correct.
Can you SSH into your octopi system? If so, what is the output of cat /etc/resolv.conf?
For more DNS utilities, you can install sudo apt-get install dnsutils (I had to sudo apt-get update and sudo apt-get upgrade before dnsutils would install).
More likely the DNS server(s) aren't being sent. I say this because the screenshot in the original post shows the 1.1.1.1 server is reachable (so gateway is correct) but name cannot be resolved. With the output of /etc/resolv.conf we can determine if nothing is being sent or if something OctoPrint can't use is being sent.