What you showed for MC's listing doesn't show a drive letter. It only shows a network path. If the naming on your network has changed in some way, MC might not be able to get to it any more.
You might try changing the path to one or two files to have Z:\ instead of \\RT-AC68P and see if that works.
If it does, you can update everything to point to Z: using the Rename, Move, and Copy tool.
To help troubleshoot this more fully, it might be helpful for you to post a screen shot from MC that shows the full filename and path for a few of your files. Then a screen shot of Windows Explorer, showing it's full path to those same files.
Brian.