If the part numbers on replacement board are the same no buffer board will be needed. If they are different then it's an upgraded board and you will need it. It a noise filter board basically.
I can plug into the door operator and change to multidrop there. But when I plug in from the ring board or MCSS, the tool says "Online to multidrop" and stops there. Can't access anything.
Some dcss and lwcss comm timeouts and errors are normal on 411,311 and Gem controllers with imotion operators. if not equipped with the buffer board. They don't require the buffer board unless the door board it upgrade to the new board. Trust me you will know right off the bat it needs it. The comm errors will just start counting up and it probably won't open or close the doors
After that, my dcss timeout faults disappeared but I had a whole new selection of faults because there was a line resistor jumper missing on the new imotion board.
Spent a month talking to tech support only to end up being advised to replace every board he knew the name of and still ended up staring at it until I figured it out on my own. But, on the plus side, I know more about 411s than I'll probably ever need to. Haha.