@robin-wales The government certifies WiFi products in your country, and it usually tries to find the balance between providing fast Internet speeds and not frying your brains too fast with radio...

@Noob_user Enable Guest Network in Deco app, it runs without the password by default.

@michalOl For this to work, Deco mesh must run in Access Point mode. See Switching a Deco to Access Point (AP) Mode

@satrapal For Connection Preference feature to work and be available in Deco app, all Deco units in Deco mesh must have firmware that supports it. Your new M4R(EU) Ver.2.0, FW: 1.6.2 has firmware...

@SwatKat Yes, you can do that without any issues.

@Raunar Try factory reset of that Deco, follow Method 2 from this document: https://www.tp-link.com/en/support/faq/1457/