Because OP doesn't say any details on which OS his Knots node operates, I don't want to make unnecessary guesses.
In addition to what others said, what about your local network and firewall settings both on the Knots and Sparrow machines? Nobody knows your local network configuration and how and/or if you secure your local network more than average John Doe.
I could assume that devices in your local network can all talk to each other without any restrictions, but frankly why should we make such an assumption?
Is there anything funky in the debug.log of Knots?
Does Sparrow happily connect and talk to your Knots node when you install and open it locally on the Knots machine? (Yes, I know, this is not exactly what you want, but if the local version works, this could indicate where to look more closely at.)
Try to approach the problem a bit more methodically and provide more details to avoid guess work.
Good questions.
On knots node I am using rpi 5 8gb with piOS. I am not very savvy with linux, so I literally built this machine, did absolutely nothing on it except install and run bitcoin knots qt. my local network shouldn't have any crazy security on it, as I just did the basic setup as a normie would. But this is something I need to look into more.
I haven't used/understood bitcoin-cli yet, hence why I am using bitcoin-qt.
My ability with the linux terminal is very light, but I have used it successfully for changing settings and troubleshooting, but of course I am just leaning heavily on grok or forum posts/tutorials.
I will try installing sparrow on knots machine and see what happens, I should have started there. Will provide update post when I have implemented/investigated everything mentioned in this post and all others in this thread so far.