Thanks for reaching out. I understand your concern about the offline issue of your Nest Protect. The most effective way to restore the connectivity or update the Nest Protect status is to force it to update.
To force update:
The LED ring briefly glows green and then turns off when the process is complete.
If the Nest Protect can't establish a connection, it says, "Try again later" and displays a yellow LED light:
If all troubleshooting is unsuccessful, assist the customer to do the following to restore the connection:
Hit this link for more troubleshooting steps.
Looking forward to your response.