This guide might be a bit dated as the 3800 series switches have been replaced by the 3810 and are approaching EoL. However, some early HPE 3800 Switches have issues with PoE and four to eight ports will fault at random times, for no apparent reason. Thus needing to be removed and replaced with newer models to via completing an RMA (usually hassle free as they have lifetime warranties).
If you simply unpatch and unplug the faulty switch and then add a new one, the newly added switch will join as a new member regardless of where in the stack it’s placed. To avoid this, we have to tell the stack which member is being replaced. We do this by entering global config mode, and then updating the member list.
1.)Fully disconnect the faulty switch you’re removing, unplug the stacking, patch, and power cables.
2.) Rack and stack the new switch, do not power it on yet.
3.) Run the commands to add the new switch to the stack
stacking member 4 type J9574A mac-address 00:11:22:33:44:55
4.) Verify it was added successfully with:
5.) Apply any port specific configurations (i.e. WAP ports, trunks, etc.)
6.) Power up the new switch
7.) Ensure connectivity
8.) Save configuration