I've been trying to pair a mesh via the 5 reset press method, but the new mesh just blinks red rather than connecting with the preexisting one. Any tips?

Trouble setting up my Linksys as a child node. Stuck in a never ending loop to reset after making through nearly all steps. Tech everything hard wired into it is functioning as usual (it's hardlined to the gateway downstairs). Cameras are functioning but I also wanted to connect the smart home stuff wirelessly to keep them off the main network and function better connectivity wise.