Fix for Episerver Google Analytics context gadget for multi-hostname websites or dedicated edit server.

FixedGoogleAnalyticsContextController.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web.Mvc;
using EPiServer.Core;
using EPiServer.GoogleAnalytics.Models;

namespace EPiServer.GoogleAnalytics.Controllers
{
    // Fixes Google Analytics context gadget for multi-hostname websites or dedicated edit server.
    [Authorize(Roles = "Administrators,GoogleAnalyticsAdministrators,GoogleAnalyticsReaders")]
    public class FixedGoogleAnalyticsContextController : EPiServer.GoogleAnalytics.Controllers.Controllers.ControllerBase
    {
        protected override bool IsGlobal => false;

        protected override AnalyticsViewModel GetViewModel(Guid gadgetId)
        {
            return ViewModelBuilder.GetContextViewModel(gadgetId, User);
        }

        public override string GetPageUrl(ContentReference contentLink)
        {
            var url = base.GetPageUrl(contentLink);
            var uri = new Uri(url, UriKind.RelativeOrAbsolute);

            // FIX: extract hostname filter for absolute urls
            if (uri.IsAbsoluteUri)
            {
                url = uri.PathAndQuery + ";ga:hostname==" + uri.Host;
            }

            return url;
        }

        protected override PartialViewResult PartialView(string viewName, object model)
        {
            // this is required for Episerver to find the views (because this controller is out of module)
            viewName = "/EPiServer/EPiServer.GoogleAnalytics/Views/Shared/" + viewName + ".ascx";
            return base.PartialView(viewName, model);
        }
    }
}

Routes.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web.Mvc;
using System.Web.Routing;

namespace Website.App_Start
{
    public static class Routes
    {
        public static void Register(RouteCollection routes)
        {
            // Fix for Google Analytics context gadget
            routes.Insert(0, new Route(
                "EPiServer/EPiServer.GoogleAnalytics/Context/{action}/{id}",
                new RouteValueDictionary(new { controller = "FixedGoogleAnalyticsContext" }),
                new RouteValueDictionary(new { action = "GraphData|PageSummaryView|ListsView" }),
                new MvcRouteHandler()
            ));
        }
    }
}