I had been having the same problems as everyone else and after reading all the complaints in all the discussions and trying every possible solution I have been able to get past this. I have an iMac, Charter cable modem (30Mbps down and 4 Mbps up) and an Airport Extreme. I determined that my problem, like others, was isolated to my home network (not songs). Found this out by setting my iPad (with Verizon Data Plan) up as a personal Hot Spot and connecting the iMac to it wirelessly. Suddenly all songs in "Waiting" status began to upload, at least until my data plan was exhausted (About 250 songs), so I knew this was a networking problem. I in no way profess to be any kind of a network guru but I researched everything possible anyway. Apple routers do not offer QoS settings. However, Apple has a piece of software for download that developers use for testing called "Network Line Conditioner". Can't remember where I found it off hand, but figured it was a safe product to try since it was an Apple product and not some third party software. Initially I had no luck modifying the direct LAN connection to the router so I disconnected the LAN cable from the iMac. I then turned on the Mac's Wi-Fi and connected to my home network. After trying several of the pre-set options in the program, I was able to find one that worked and I slowed down my Upload speed and made a 1% allowance for dropped packets (My custom setting, I'm not sure I even know what dropped packets are). Don't know what this fixed or what the problem really was but my songs in "Waiting" now upload without problems or failures or restarting. The (GUI) program is very easy to use and simple to turn "On" and "Off". When "On" it resides up top near the "Signal Strength" indicator and is selectable with a "Right Click". I can't promise that this will work for any or all but I wanted to share my success. Maybe others can elaborate on my lack of "Network Knowledge" and explain this a little better. Good luck to all!
