okay, let's give this a whack.

utils/he_ipv6/ref

@@ -2,3 +2,6 @@
 # https://forums.he.net/index.php?topic=3153.0
 # https://gist.github.com/pklaus/960672
 # https://shorewall.org/6to4.htm#idm143
+# https://genneko.github.io/playing-with-bsd/networking/freebsd-tunnelv6-he
+# https://journeymangeek.com/?p=228
+# https://superuser.com/questions/1441598/using-a-hurricane-electric-tunnel-to-provide-ips-to-a-network-with-dnsmasq/1441604#1441604

utils/he_ipv6/tunnelbroker.py

@@ -106,6 +106,17 @@ class TunnelBroker(object):
                           '{2}').format(self.iface_name, self.iface_idx, e))
             ipr.close()
             raise e
+        try:
+            ipr.route('add',
+                      dst = 'default',
+                      # gateway = self.def_rt_ip,
+                      oif = self.iface_idx,
+                      family = socket.AF_INET6)
+            logger.debug('Added default route for link {0}.'.format(self.iface_name))
+        except Exception as e:
+            logger.error(('Could not add default IPv6 route on link {0}: {1}').format(self.iface_name, e))
+            ipr.close()
+            raise e
         for alloc in self.tun.allocations:
             try:
                 ipr.addr('add',
@@ -118,17 +129,7 @@ class TunnelBroker(object):
                               '{2}').format(str(alloc.ip.str), alloc.iface_idx, e))
                 ipr.close()
                 raise e
-        try:
-            ipr.route('add',
-                      dst = 'default',
-                      gateway = self.def_rt_ip,
-                      oif = self.iface_idx,
-                      family = socket.AF_INET6)
-            logger.debug('Added default route for link {0}.'.format(self.iface_name))
-        except Exception as e:
-            logger.error(('Could not add default IPv6 route on link {0}: {1}').format(self.iface_name, e))
-            ipr.close()
-            raise e
+        # Is this necessary?
         # try:
         #     ipr.route('add',
         #               dst = '::/96',
@@ -152,7 +153,7 @@ class TunnelBroker(object):
         try:
             ipr.route('del',
                       dst = 'default',
-                      gateway = self.def_rt_ip,
+                      # gateway = self.def_rt_ip,
                       oif = self.iface_idx,
                       family = socket.AF_INET6)
             logger.debug('Removed default route for link {0}.'.format(self.iface_name))