Yes, there is a solution for redirecting old URLs when migrating from Invision (IPS) to XenForo, similar to the plugin available for vBulletin. During the migration, XenForo provides tools and guidance to help set up redirects so that old URLs from Invision can point correctly to the new URLs on XenForo, preserving your SEO and link structure.
To handle this, you usually need to use a combination of a redirect script and server configuration changes (using .htaccess on Apache or web.config on IIS). These scripts or plugins are typically part of the migration tools provided by XenForo or available in the community as add-ons. They help ensure that any links to your old forum URLs (like posts, threads, or categories) will automatically redirect users to the appropriate new locations in the XenForo structure.
It's important to set this up correctly to prevent broken links and maintain your current SEO rankings. Many forum administrators use third-party services or hire developers familiar with both platforms to ensure a smooth transition, especially with a large number of posts like your 738.7k. You should also check XenForo’s official resources and community forums for specific scripts and best practices.