Ever since my move to a new apartment, I was frustrated by some of my network files going offline randomly and staying offline for 5 minutes or up to an hour or two. The weirdest part was that it would only happen to the network files that were in a path with Offline Files enabled. As a result, I would periodically lose access to files that were not marked “Always available offline”, and I would get frequent synchronization conflicts for any files that were still available offline.
Another symptom of this problem was that I could map a separate drive letter to the same or deeper path, not enable Offline Files for the networked drive, and then have no trouble with the files when I try to use the drive letter. I could even browse shared folders using the server’s UNC path at the same time as my Offline Files cache seemed to be stuck offline.
I had several suspicions about why this was happening. First of all, I had started using Wi-Fi networking on my desktop computer as a convenience until I could knock some holes in the apartment walls to run proper Ethernet cables. The signal quality seemed good enough that I shouldn’t have persistent connection problems, yet the Offline Files system seemed central to the problem. I eventually discovered that the Client Side Cache “slow link” mode was at fault for this whole mess.