@gandalf1369 There are certain situations (very rare) that this could happen: 1. When the router works as an AP or a wireless switch - details. 2. When hardware NAT (NAT Boost) is disabled -...

@vncz If the Deco is in router mode this could work but you should not connect to this switch anything else since that may cause a network loops. One more thing - don't use a D-Link switch for that...

@vncz When in router mode main Deco should be connected directly to the modem - details. When using ethernet backhaul you can refer this FAQ and read through this thread. If Deco is about to be used...

@M-collins_0929 Review your RE605X configuration. If nothing helps, I would recommend to reset the RE to its factory defaults and re-configure from scratch using this video guide. To reset the RE...

When building a mesh network with a range extender there's a known limitation that won't allow you to extend the main router guest and IoT networks through the RE.

@DonI49 I believe this is by design - web management access to be allowed only from the management VLAN 1. Here's a story which describes why Multi-VLAN mode APs may not work with different VLANs...