@Portway X10 is good additions on hardware side. The thing to consider is X10 firmware appears to be one version behind M5's. If you are using one of the following features in your Deco mesh you may...

@gumpdeco88 When two networking devices, such as Main Deco and ISP modem/router connect by Ethernet cable, they negotiate discrete Ethernet speed between them. They can either agree on 100Mbps or on...

@gumpdeco88 It is possible that your Main Deco negotiated 100Mbps speed over wired link to ISP modem/router. Try different Ethernet cable. Also check Deco app, if you see Abnormal WAN Port Speed...

@NefariousLegion You made a good choice. That switch will assist with troubleshooting, when necessary. Once, I spent countless hours trying to figure why one of my wired Satellites became slow, only...

@NefariousLegion Yes, you can. This is how I run my 3 nodes Deco mesh with 2.5Gbps ports and modem/router with single 2.5Gbps port. To avoid any issues, buy switch from TP-Link brand. Also, I would...

@LYO_Tomek Please share network diagram, what switches you use, Deco PoE firmware version(s), how long have you had these Deco, when did you upgrade firmware (if you did), was the issue present...