The problem
When your forum is embedded into a page of your website, Safari treats the cookies that the forum sets as third-party cookies. The Safari browser blocks third-party cookies by default. As a result, members who open your website in Safari may be taken to the login page instead of the forum, or may be signed out again right after they log in. The same members can log in normally in other browsers.
The solution
Connect your domain to your forum so that your forum and your website use the same root domain. For example, forum.yourdomain.com for a website at yourdomain.com. Safari then considers the cookies first-party, so they are always accepted and members stay logged in.
If your domain host is not listed, see the instructions for each domain provider. For more detail on what Safari does with an embedded forum, see Using the embed code in Safari.
Wix and Google Sites
The embed code is not supported on Wix or Google Sites. If your website is built on one of these platforms, link to your forum instead of embedding it. See how to add your forum to a Wix website or how to add your forum to a Google Sites website.