@my2108 In that case, here is another option to try. TP-Link offers beta firmware for Deco M9 Plus: https://community.tp-link.com/en/home/forum/topic/574954 After you install it, the "preferred...

@Tiz One more thing to check. Bring Satellite Deco to where Samsung TV is, connect TV to Satellite Deco with Ethernet cable. If that works, you might have IPTV enabled for the second port of Main...

@Liwiu You need to find your M4 hardware version. See How to find the hardware version on a TP-Link device If it is hardware V4, there is new firmware for it with that feature:...

@Tiz Usually, connecting Smart TV by Ethernet to Deco unit fixes such issues. I would suggest three troubleshooting steps: 1. Verify that TV uses Ethernet link while connected by Ethernet cable. I...

@Kiruto If your Deco mesh consists of M5s, follow the second part of this document to configure smartphone connect on 5GHz: How to select a preferred signal source on the Deco App Before configuring...

@my2108 This setup offers multiple options to try. I suggest to start with the simplest. Do your security cameras support WiFi 5? If they do, my recommendation would be to turn off 2.4GHz for Deco...