You should never need to open ports for traffic originating from your network. Your device is negotiating a connection to the server to download a file. Similar to not having to open any ports to browse websites.
I’ve tried 2 different RP3 on a known working LAN. It appears it’s not seening the LAN and then tries going to connect on WiFi after awhile. I suppose I can try the wifi USB stick option, but the ethernet not working on two different RP3 and known working LAN tells me that something with my Router isn’t properly talking to the RP3. I’d rather tackle the LAN issue. Unifi Security Gateway has all ports closed by default. So, I’m thinking I need to Port forward to the RP3’s IP Address for it to work. I just do not which ports are needed.
INBOUND ports are closed. You absolutely do NOT need to forward ports on your router to a pi for it to get a connection. That is NOT how basic networking works.