rpc pool: drop hive-api.3speak.tv, which never completes a TCP connect

dotnet/EcencyApi.Tests/HiveRpcFailoverTests.cs

@@ -474,8 +474,13 @@ public async Task ASuccessClearsAFailurePark()
     [Fact]
     public void DefaultPool_DoesNotCarryTheUnreachableNode()
     {
+        // Nodes dropped for never completing a TCP connect. A node that answers
+        // nothing costs a full per-node timeout every time the ordering reaches
+        // it, which is every cold start and every lapsed park.
         Assert.DoesNotContain(HiveClients.DefaultNodes, n => n.Contains("arcange", StringComparison.Ordinal));
+        Assert.DoesNotContain(HiveClients.DefaultNodes, n => n.Contains("3speak", StringComparison.Ordinal));
         Assert.True(HiveClients.DefaultNodes.Count >= 6);
+        Assert.Equal(HiveClients.DefaultNodes.Count, HiveClients.DefaultNodes.Distinct().Count());
     }
 
     [Fact]

dotnet/EcencyApi/Infrastructure/HiveRpcClient.cs

@@ -434,16 +434,21 @@ public static class HiveClients
     // portfolio engine/chain layers came back empty for everyone. GetAccounts
     // also routes around such a node at runtime, but keeping them out of the pool
     // means correctness here does not depend on that fallback firing.
-    // hive-api.arcange.eu is absent too: it never completes a TCP connect from
-    // any host this service runs on (SYN, no answer), so every attempt cost the
-    // full per-node timeout and, in bursts, took every in-flight fill with it.
+    // hive-api.arcange.eu and hive-api.3speak.tv are absent for the same reason
+    // as each other: neither completes a TCP connect from any host this service
+    // runs on (SYN, no answer, on 443 and on 80), so every attempt cost the full
+    // per-node timeout and, in bursts, took every in-flight fill with it. A node
+    // that answers nothing is worse for the pool than a slow one, because the
+    // health tracker learns latency from answers and has none to learn from: it
+    // parks after three consecutive failures, the park lapses, it is probed
+    // again. While unparked it sits in config order, which is where any
+    // unproven latency profile starts.
     public static readonly IReadOnlyList<string> DefaultNodes = new[]
     {
         "https://api.hive.blog",
         "https://api.deathwing.me",
         "https://rpc.mahdiyari.info",
         "https://api.openhive.network",
-        "https://hive-api.3speak.tv",
         "https://api.syncad.com",
         "https://api.c0ff33a.uk",
     };