See the workarounds below if either one will work:
Workaround 1: When the node is set up with a managed switch as pictured below, your devices will not be able to connect to the child node’s WiFi unless the managed switch is configured to forward and allow VLAN 3 and VLAN 4 traffic on all ports connecting to a node. These two VLANs are needed for the WiFi setup to function. You must configure VLAN on a Linksys Managed Switch or a Linksys Smart Switch. No configuration is needed for unmanaged switches.
Workaround 2: When the node is set up with a managed switch as pictured above, turn OFF HomeKit Integration from the Linksys app and power cycle all child nodes. As a trade-off, you cannot link the node to the Apple® Home app. For complete instructions, follow the steps below:
1. Log in to the Linksys app.
2. Tap the menu icon at the upper-left corner of the screen and then tap Network Administration.
3. Turn OFF the HomeKit Integration button.