Hi KMILESIM, thank you for posting in Apple Support Communities.
So sorry that you are having trouble syncing your iPad with your computer and the following link explains what the Error Code 54 is and how to resolve the error through a number of steps:
https://support.apple.com/en-au/HT205597
However, is it always suggested that you update your iPad to the most recent iPadOS which is 15.2.1 and the following link will explain how to do this:
https://support.apple.com/en-au/guide/ipad/ipad9a74c576/ipados
Although if what appears in your post is correct you may not be able to update as it shows you may have an iPad Mini (introduced in 2012) that can only be updated to IOS9 and the following link will show this:
https://support.apple.com/en-us/HT201222
Therefore can I suggest you consider upgrading your iPad as Apple and developers regularly update their software and apps to provide security improvements and enhancements and these may not work well anymore on the iPad. Furthermore, you may also experience problems accessing websites.
You are also able to contact Apple Support should the issue persist.
You can do this as follows: