diff --git a/internal/pmtud/pmtud.go b/internal/pmtud/pmtud.go
index a7d23fe6..5c94da85 100644
--- a/internal/pmtud/pmtud.go
+++ b/internal/pmtud/pmtud.go
@@ -132,18 +132,17 @@ func pmtudMultiSizes(ctx context.Context, ip netip.Addr,
 		// cannot be working if we had a timeout.
 		for i := len(tests) - 2; i >= 0; i-- { //nolint:mnd
 			if tests[i].ok {
-				return pmtudMultiSizes(ctx, ip, tests[i].mtu, tests[i+1].mtu,
+				return pmtudMultiSizes(ctx, ip, tests[i].mtu, tests[i+1].mtu-1,
 					pingTimeout, logger)
 			}
 		}
 
-		// All MTUs failed.
-		if tests[0].mtu == minMTU+1 {
+		if tests[0].mtu == minMTU+1 { // All MTUs failed.
 			return minMTU, nil
 		}
 		// Re-test with MTUs between the minimum MTU
 		// and the smallest next MTU we tested.
-		return pmtudMultiSizes(ctx, ip, minMTU, tests[0].mtu,
+		return pmtudMultiSizes(ctx, ip, minMTU, tests[0].mtu-1,
 			pingTimeout, logger)
 	case err != nil:
 		return 0, fmt.Errorf("collecting ICMP echo replies: %w", err)
@@ -152,14 +151,17 @@ func pmtudMultiSizes(ctx context.Context, ip netip.Addr,
 	}
 }
 
-// Create the MTU slice of length 8 such that:
+// Create the MTU slice of length 11 such that:
 // - the first element is the minMTU plus the step
 // - the last element is the maxMTU
 // - elements in-between are separated as close to each other
 // - Don't make the minMTU part of the MTUs to test since
 // it's assumed it's already working.
+// The number 11 is chosen to find the final MTU in 3 searches;
+// to find it in 2 searches requires 37 parallel queries which
+// could be blocked by firewalls.
 func makeMTUsToTest(minMTU, maxMTU int) (mtus []int) {
-	const mtusLength = 8
+	const mtusLength = 11 // find the final MTU in 3 searches
 	diff := maxMTU - minMTU
 	switch {
 	case minMTU > maxMTU:
diff --git a/internal/pmtud/pmtud_test.go b/internal/pmtud/pmtud_test.go
index 45879a92..e6513395 100644
--- a/internal/pmtud/pmtud_test.go
+++ b/internal/pmtud/pmtud_test.go
@@ -27,20 +27,20 @@ func Test_makeMTUsToTest(t *testing.T) {
 		},
 		"0_12": {
 			maxMTU: 12,
-			mtus:   []int{2, 3, 5, 6, 8, 9, 11, 12},
+			mtus:   []int{1, 2, 3, 4, 5, 7, 8, 9, 10, 11, 12},
 		},
 		"0_80": {
 			maxMTU: 80,
-			mtus:   []int{10, 20, 30, 40, 50, 60, 70, 80},
+			mtus:   []int{7, 14, 21, 28, 35, 42, 49, 56, 63, 70, 80},
 		},
 		"0_100": {
 			maxMTU: 100,
-			mtus:   []int{12, 24, 36, 48, 60, 72, 84, 100},
+			mtus:   []int{9, 18, 27, 36, 45, 54, 63, 72, 81, 90, 100},
 		},
 		"1280_1500": {
 			minMTU: 1280,
 			maxMTU: 1500,
-			mtus:   []int{1307, 1334, 1361, 1388, 1415, 1442, 1469, 1500},
+			mtus:   []int{1300, 1320, 1340, 1360, 1380, 1400, 1420, 1440, 1460, 1480, 1500},
 		},
 	}