Maybe try adding 1.5 seconds delay on refresh rate change on those 2820 boxes, could give the box enough time to start playback synced from the get go.. Worth a try.
Main System - HTPC - Intel I3 6300 - Asrock z170 - 16 GB DDR4 - 128gb SSD - 65" UHD HDR Sony Android TV - Pioneer VSX 1130-K - 7.2.2 speakers
Other devices currently in use - 55" 3D UHD LG TV - 2 Fire TV's - Nexus Player - MiniMX s905 - Voyo Vmac Mini
Ubuntu Server - 12 TB NAS - MYSQL - Torrent Box