Mongodb Realm doesn’t support LINQ contain and any?

In Unity, I’m using Realm to sync with my MongoDB database. When I try to filter the results using the following code:

var dbMatchgames = realm.All<DBMatchgame>().Where(i => i.PlayerIDs.Contains(MyApp.CurrentUser.Id));
realm.Subscriptions.Add(dbMatchgames, new SubscriptionOptions() { Name = "MyMatchgame" });

I get an error saying that the Contains method is not supported. How can I avoid downloading all the documents in a collection?