I have migrated my multisite from an unmanaged vps

Hi,

I have migrated my multisite from an unmanaged vps to a managed one (SiteGround). After I restored the site I cannot log in to the site with my admin account. I am not getting an incorrect message and I am sure it is correct as it is the admin account from the source site. It just redirects back to the login screen with url like ( https://trainerous.com/wp-login.php?redirect_to=https%3A%2F%2Ftrainerous.com%2F%2Fwp-admin%2F&reauth=1 ).

I have cleared browser cache and still no joy. Anyone have an idea?