diff --git a/nodedb.py b/nodedb.py
index f60cf12..ebaf720 100644
--- a/nodedb.py
+++ b/nodedb.py
@@ -284,9 +284,19 @@ class NodeDB:
         if data[2]:
           node.name = data[2]
 
+# 1043nd, vpn, wlan, br-wan
+
 # compares two MACs and decides whether they are
 # similar and could be from the same node
 def is_similar(a, b):
+# a is the base address
+# b is some mac of the host
+# b = 00:00:00:00:00:+1 x
+#     |2:00:00:+1:00:+1 x
+#     |2:00:00:00:00:+1 x
+#     |2:00:00:00:00:+2
+#     |2:00:00:+1:00:00
+
   if a == b:
     return True
 
@@ -296,20 +306,29 @@ def is_similar(a, b):
   except ValueError:
     return False
 
-  # first byte must only differ in bit 2
-  if mac_a[0] | 2 == mac_b[0] | 2:
-    # count different bytes
-    c = [x for x in zip(mac_a[1:], mac_b[1:]) if x[0] != x[1]]
-  else:
-    return False
+  x = mac_a
+  x[5] += 1
+  if mac_b == x:
+    return True
 
-  # no more than two additional bytes must differ
-  if len(c) <= 2:
-    delta = 0
+  x[0] |= 2
+  if mac_b == x:
+    return True
 
-  if len(c) > 0:
-    delta = sum(abs(i[0] -i[1]) for i in c)
+  x[3] += 1
+  if mac_b == x:
+    return True
 
-  # These addresses look pretty similar!
-  return delta < 8
+  x = mac_a
+  x[0] |= 2
+  x[5] += 2
+  if mac_b == x:
+    return True
 
+  x = mac_a
+  x[0] |= 2
+  x[3] += 1
+  if mac_b == x:
+    return True
+
+  return False