I have recently installed Kubuntu 20.04 after having successfully used earlier LTS versions for over 10 years, and have set up static IP addresses (in order to use openSSH on my home network) for most of that time. In earliest versions, I configured the /etc/network/interfaces file manually. In later versions, that didn't work, but I was able to configure the static IP using WICD. But now WICD apparently is no longer available for Kubuntu 20.04 -- at least, I haven't been able to find how to install it.

Now I've learned that the CLI file /etc/netplan/01-network-manager-all.yaml is what I have to use to configure a static IP address for my wireless connections. I've written the file according to several sources I've found online, but the static IP assignment is ignored.

The result of running ifconfig is (in part):
My /etc/netplan/01-network-manager-all.yaml file is:
[I'm using dots, here, to simulate the indentations in the actual file, but which are ignored in this posting environment.]

I can run netplan generate without getting any error messages, and running netplan apply shuts down my current wifi connection, then brings it back up. However, the IP address remains the same as before (102, when I'm trying to assign it as 20).

FWIW, the wifi on another machine (running Lubuntu 18.04) on my network will still successfully log on at the static IP assigned to it with WICD.

Since it's NetworkManager, use nmcli to dig around.
Also use troubleshooting instructions at https://netplan.io/troubleshooting.

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