Zoho Assist failed to use unattended link

Zoho Assist failed to use unattended link

I'm new and trying to use/test an unattended mode to be able to use remotely my Samsung android phone from my iPhone.
I can send an activation link/email to my email, but every time the unattended activation fails with message below:

This site can’t be reached

Check if there is a typo in null

DNS_PROBE_FINISHED_NXDOMAIN

Please help,
On both phones I'm using the same account/email
-Mike