@glenb You need to upgrade Main Deco M5 to firmware 1.6 beta, which has an option of turning off Smart DHCP for Deco running in AP mode. See here: [New Firmware] Deco M5 1.6.0

@AK32 A lot has changed since 2020, when this topic was discussed. By utilizing Deco Guest Network, you can have two different SSID: one for 5GHz and one for 2.4GHz.

@Pip60 See if this forum conversation can give you ideas, it is for S4 but M4 is similar and also there is general discussion on that topic with helpful hints: Deco S4 power adapter barrel plug size

@MariaZika You can try my recommendation, and if you find Access Point mode is not working for you, you can change it back to what it was before, i.e., Router mode. I run my Deco mesh in Access Point...

@MattCullum If you can run Deco mesh in Access Point mode, you can wire M5 any way you want to, including connecting them all to ISP Router. In Deco Router mode, which is default mode, you can not...

@MattCullum There is no universal solution, so you'll need to do a bit of assessment what will work for you. 1. Check your Satellite M5 Decos - do they connect to the correct (nearest) to them Deco?...