Can't connect to local server with led light fast blinking cyan

Since last week, my core encounter a problem when connect to my local server (the core is already loaded the local server public key),that when the core finishes connect it to the wifi network, the core blinks the cyan color very fast and never breath, and the local server has no debug information,

this is my short video:

It sounds like you might need to reflash the keys for your local server on the core, and update the server’s copy of the public key.

reflash the keys for my local server? I don’t get it.
does it mean I need to rebuld the public key on the server side and save it into the core again or reversely save the core’s public key into the server folder again ?

I would try both since they both need to be correct.