DIAGNOSIS The mesh backhaul is working (hence the blue light), but the node's communication channel with the main node for management data is glitched. It's online but not "checked in."
FIX Restart the Velop system from the app. In the Linksys app, go to the problematic node's settings (if you can see it) or the main node's settings, find "Restart" or "Reboot," and confirm. Wait 5 minutes. This soft reboot via software often re-establishes the management link without you touching the hardware.
IF THAT DIDN'T WORK The node might need a factory reset and re-addition. Press and hold the reset button on the bottom of the unreachable node for 10 seconds until the light flashes red. Release. The node will reboot and appear as a new node in the app. Use the app's "Add a Node" feature to re-pair it to your mesh.
HEADS UP A factory reset on a satellite node won't nuke your main network settings, but you will lose any custom device prioritization or port forwarding rules specific to that node.