@BarisOz For troubleshooting purposes, it would help if you can clarify what do you have as a "modem:" is it just modem, or gateway? If you are not sure, give its brand and model number and I'll...

@RickyM E4 has 100Mbps Ethernet ports, not a good choice if your Internet speed is faster than 100Mbps. The rest have gigabit Ethernet ports. These all are WiFi 5 Deco. TP-Link also has Deco M5, S7...

@doozanic On Satellite Deco all ports are LAN. You will not need a switch if you want to connect two computers. Also check Deco X50 and X55: they have three Ethernet ports.

@titi25 Disabling Deco mesh WiFi from Deco app is easy: just change Main Network password and don't share new password with anyone. To enable WiFi, restore Main Network password to what it was...

@natajacks Yes, it should be fine. See How to add an additional unit to your Deco network

@David-TP This will be Wi-Fi 7 Deco without support for 6 GHz band. Asking for clarification here, because even TP-Link's own document "What is Wi-Fi 7?" has table comparing different WiFi protocols...