Not working on PC but working fine on my tablet

What is the problem?
After an Update I can't find the Raspberry Pi with Octoprint in the Wifi on my Pc and my Phone.
The strange thing is that I easily can log in to Octoprint with my Tablet und another Pc is also working.
Before the Update everything worked perfect.

What did you already try to solve it?
I did an IP Scan). The IP Scan shows that the Pi ist not connected to the Wifi.

Logs (syslog, dmesg, ... no logs, no support)

Additional information about your network (Hardware you are trying to connect to, hardware you are trying to connect from, router, access point, used operating systems, ...)

I am using my Wifi Router for the connection

You wouldn't happen to know what update you did? That would be the most useful thing to know here.

I am confused by some logic here - if the tablet and another PC are connecting, but it is not showing up in an IP scan... Are you sure the IP address has not changed? Using http://octopi.local to connect or something else?

Thank your for help.
Yesterday it did not work but today everything works again and I changend nothing.

^ Which one?