Everything was fine under Mojave, but when I upgraded to Catalina my Mac can no longer connect to my Windows 10 NAS. It's not the NAS because I have other Windows 10 and even Raspberry Pis connecting to it. I can see all of my computers on the network through Finder, I just cannot connect to any of them.
I started with this post to create an nsmb.conf file because my system did not have one. Not sure if it did under Mojave because I didn't have a problem, so I am assuming it did not have one.
https://macintoshhowto.com/advanced/how-to-speed-up-network-drives-on-os-x-mojave.html
When that did not work, I reviewed the following post and it still did not resolve my problem.
What causes some Network Drives using SMB no longer connect to macOS Catalina?
It's frustrating that something that should be so very easy has become so very difficult.