ssh "Connection timed out" after first reboot of a Raspberry Pi

I am trying to setup an Ubuntu 20.04 Server on a Raspberry Pi 4+ (RPi). Everything works and I can ssh in without a problem the first time the server starts up, both using Ethernet and WiFi. However, if I reboot the RPi, I get a: ssh: connect to host 10.0.0.16 port 22: Connection timed out message. I have tried booting the RPi without changing any other settings other than adding the WiFi information. Here is my network-config file:

version: 2
ethernets: eth0: # Rename the built-in ethernet device to "eth0" match: driver: bcmgenet smsc95xx lan78xx set-name: eth0 dhcp4: true optional: true
wifis: wlan0: dhcp4: true optional: true access-points: "<router-name>": password: "<router-password>"

I can use arp –na | grep –i ... on the RPi (when not remote) and see my laptop's IP and arp -a | findstr ... on my Windows machine to see my RPi IP.

I haven't seen any good answers to this question elsewhere. My thinking is that the cloud-init first boot information works for the first startup but then does not work for subsequent restarts. The weird thing is, I am still able to use the internet when physically login on to the RPi (run apt install to install net-tools for example) even using WiFi so some setting must still load from cloud-init. Could ssh become disabled after first boot? Not sure how to fix this, even if this is the case.

Has anyone else had this problem, and if so, have you found a workaround?

Thanks!

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