diff --git a/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.IntegrationTests/AbLegacyDeadDeviceIsolationTests.cs b/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.IntegrationTests/AbLegacyDeadDeviceIsolationTests.cs
index 2e5be188..64eb19fb 100644
--- a/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.IntegrationTests/AbLegacyDeadDeviceIsolationTests.cs
+++ b/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.IntegrationTests/AbLegacyDeadDeviceIsolationTests.cs
@@ -47,19 +47,23 @@ public sealed class AbLegacyDeadDeviceIsolationTests(AbLegacyServerFixture sim)
         await drv.InitializeAsync("{}", ct);
         string[] refs = ["Live", .. dead.Select(d => d.Name)];
 
-        var sw = Stopwatch.StartNew();
-        var first = await drv.ReadAsync(refs, ct);
-        sw.Stop();
+        // Two consecutive comms faults mark the device down. With coalescing on, the dead device's 20 tags are ONE
+        // block (one fault per poll), so the window can open on the second poll rather than the first — either way
+        // at most two timeouts are paid before the device stops being dialled.
+        var total = TimeSpan.Zero;
+        TimeSpan last = default;
+        for (var poll = 0; poll < 3; poll++)
+        {
+            var sw = Stopwatch.StartNew();
+            var r = await drv.ReadAsync(refs, ct);
+            sw.Stop();
+            total += last = sw.Elapsed;
+            r[0].StatusCode.ShouldBe(AbLegacyStatusMapper.Good, $"poll {poll}: the live device must be served in the same poll");
+            r.Skip(1).ShouldAllBe(s => s.StatusCode != AbLegacyStatusMapper.Good);
+        }
 
-        first[0].StatusCode.ShouldBe(AbLegacyStatusMapper.Good, "the live device must be served in the same poll");
-        first.Skip(1).ShouldAllBe(s => s.StatusCode != AbLegacyStatusMapper.Good);
-        sw.Elapsed.ShouldBeLessThan(timeout * 3, "a dead device may cost at most two timeouts per backoff window");
-
-        sw.Restart();
-        var second = await drv.ReadAsync(refs, ct);
-        sw.Stop();
-        second[0].StatusCode.ShouldBe(AbLegacyStatusMapper.Good);
-        sw.Elapsed.ShouldBeLessThan(timeout, "inside the backoff window the dead device is not dialled");
+        total.ShouldBeLessThan(timeout * 2.5, "a dead device may cost at most two timeouts per backoff window");
+        last.ShouldBeLessThan(timeout, "inside the backoff window the dead device is not dialled");
         drv.GetHealth().State.ShouldBe(DriverState.Degraded);
     }
 }