To Many Redirects

I am embarressed bringing this subject up as there are a wealth of articles about it and plugins however I cannot resolve the issue.

I have tried resetting permalinks, deactivating all plugins, removing those that may have any impact on routing, blanked my .htaccess file then built it back bit by bit, installed 3 different plugins and can’t resolve the issue. Yoast comes in for a bit of flack on this and I have removed it entirely. Of course I have played endlessly with the conical settings.

Unlike some my site https://fernleafconsulting.co.uk runs fine. However when I try to create a post or page or user I get the redirect error. When a user tries to register he gets the same.

I have this code running:

// Add page after new user registered
    add_action('user_register', 'registration_newpage');

    function registration_newpage($user_id) {

        $user_info = get_userdata($user_id);
        $username = $user_info->user_login;
        $post = array();
        $post['post_name']    = 'Members-Page-for-'.$username; // The name (slug) for the page
        $post['post_type']    = 'page'; //could be 'page' for example
        $post['post_content'] = esc_attr($username.' - This page was created for you and any messages that we need to send you with regards to any products, services or changes to your membership will be posted here.'.$userid);
        $post['post_author']  = $username;
        $post['post_status']  = 'publish'; //status
        $post['post_title']   = 'Members Page for '.$username;
        $postid = wp_insert_post ($post);
        if (!$post_id) {
            wp_die('Error creating template page');
        } else {
            update_post_meta($post_id, '_wp_page_template', 'page-members.php');
        }
        return;
    }

which illustrates what happens. I create a user it gets a redirect error but the user is created. This code fires but fails wp_insert post although the page is created but without the template.

Any help would be greatfully received.