Fix issue with using Python 2 not 3
diff --git a/xos/services/vpn/admin.py b/xos/services/vpn/admin.py
index f0b8f7c..75fa9ca 100644
--- a/xos/services/vpn/admin.py
+++ b/xos/services/vpn/admin.py
@@ -181,16 +181,16 @@
         self.instance.clients_can_see_each_other = self.cleaned_data.get(
             'clients_can_see_each_other')
 
-        self.instance.failover_servers.clear()
+        self.instance.failover_servers[:] = []
         for tenant in self.cleaned_data['failover_servers']:
-            self.instance.failover_servers.add(tenant)
+            self.instance.failover_servers.append(tenant)
 
         self.instance.protocol = self.cleaned_data.get("protocol")
         self.instance.port_number = (
             self.instance.provider_service.get_next_available_port(
                 self.instance.protocol))
 
-        self.instance.use_ca_from.clear()
+        self.instance.use_ca_from[:] = []
         self.instance.use_ca_from.append(self.cleaned_data.get('use_ca_from'))
         result.save()  # Need to do this so that we know the ID
 
diff --git a/xos/services/vpn/models.py b/xos/services/vpn/models.py
index b4ff12f..6b76575 100644
--- a/xos/services/vpn/models.py
+++ b/xos/services/vpn/models.py
@@ -94,7 +94,7 @@
                           'script_text': None,
                           'pki_dir': None,
                           'use_ca_from': list(),
-                          'failover_servers': set(),
+                          'failover_servers': list(),
                           'protocol': None}
 
     def __init__(self, *args, **kwargs):