@GeraldoCWB In all my tests with Deco M5 I never got WiFi speeds faster than 475Mbps. I ran very many tests, in almost ideal conditions. Which means, you are getting as much from Deco M5 as it is...

@Piers As an owner of multiple Deco M5s I can tell you that you have defective unit. Return it to seller. Buy M5 from different seller, if you can get working unit you won't be disappointed. Next...

@Achilleas Main Deco M5 can provide WiFi speeds of up to 500Mbps. Which means, if you ever decide to upgrade your Internet speed, you can go up to 500Mbps without need to replace Deco M5 hardware....

@Joakim77 Thanks for the picture, it helps a lot. Yes, the box with "telenor" on it must be ISP Router. It is connected to Ethernet switch TL-SG105E. If this setup was done by the Internet provider,...

@krisw In regard to rearranging, you may be overthinking it. It should be easy. Get "RJ45 network coupler" which looks like this: Unplug Main Deco from both Ethernet cables, plug them to network...

@krisw ISP routers usually come with more than one Ethernet port. If yours has at least two, it means you can connect switch directly to the router and whatever connected to another port - connect it...