Hi Michael, As recent as six months ago OS10 did not support stacking according to another posting on this forum: https://www.dell.com/community/Networking-General/Stacking-2-S4128-switches/td-p/6066275. The post does provide information on alternatives, such as VLT. Also, check the user guide for your OS version for stacking commands to see if it is supported with that particular version. Otherwise one of the other solutions may provide you with what you need. Hope this helps