I tried upgrading again to Mojave and have an issue. My iTunes library is on a QNAP NAS. Syncing songs to my iphone 8 plus or x works fine and is fast on High Sierra. Once I upgraded to Mojave, it takes several minutes to sync each song from the gigabit nas (wired or wireless) to the phone. This happened on the last couple of builds. Once I move back to HS, it syncs 100 songs in just a few minutes. I've gone back and forth a couple of times without any changes to the NAS or other networking bits.
Any ideas?