@a_sh Thanks. Will wait on your update for #1 and #4. For #1, ISP Router brand and model name can often be found on the label on the bottom of the router. Please also do the following two...

@Don_Bro You can add Deco X50-Outdoor to your Deco E4 WiFi mesh and they will run together. It would make sense at some point to also replace E4 with 3-unit set of Deco X50 or Deco X55. This will...

@RonMid Short answer: it is not possible. Long answer can be found here, in discussion of all TP-Link WiFi mesh offerings: TP-Link Deco Mesh vs EasyMesh vs OneMesh vs Omada Mesh What's the Difference?

@David-TP I've seen two explanations from TP-Link Support why Deco band steering logic can move device to 2.4 GHz, have found one of them here:...

@a_sh a_sh wrote @Alexandre. thanks for your answer, failed mean that all Decos become red and there is no wifi at home. Which most likely means Main Deco lost connection to the Internet. Let's...

@Zyber Main Deco must always be connected with Ethernet cable to the router.