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Yes same LAN network. I configured the DHCP on the node PC. The local ip's are correct according to my router. The WAN ip is changing though.
If you use LAN/local IP to make connection between Sparrow and your node, the WAN IP doesn't matter.
The firewall has allowances for both Bitcoin core and sparrow. Do I need do more indepth config than just the "add program" option?
No, AFAIK "add program" on Windows firewall allow all kind of connection.
I also just tried installing sparrow on the node PC and it won't connect to node either.
Have you checked Bitcoin Core
debug.log file to see if there's relevant message (such as blocked connection) when you open Sparrow Wallet on the node PC?