I had sync issues and after doing research and testing different servers I found I had the issue with only 1 specific server. ******. Any other server I use on this box runs fine. So if u have issues u may need to test different options.
see i dont think it was server but what model of 4k box when you got it when first came out good later troubles then good again this is what i saw happening and what i mean by that was what version it loaded at start