Why are some TP-Link Decos devices intermittently appearing offline?

I have a Deco mesh network which has been working flawlessly for over 2 years. It uses 4 deco units (all X20 models) and the decos are designated as follows: House (the main unit), Office, Studio, and Cabin. They are all connected via Ethernet as follows: Modem House House Ethernet Switch Ethernet Switch Office Ethernet Switch Studio Studio Cabin About 6 months ago I removed the Studio deco and used an Ethernet cable to connect the two data ports in the studio together (i.e. cable connected between the data port from the house and the data port to the cabin). This was done because we weren’t u

Question by Monomeeth on Super User, licensed CC BY-SA. We show a short excerpt and link to the original thread as credit.