Comment 1 for bug 1966135

While chatting with Frode Nordahl, he suggested the following quick fix (that I have not tested):

diff --git a/src/lib/charm/openstack/ovn_central.py b/src/lib/charm/openstack/ovn_central.py
index d9cd65b..f5ba614 100644
--- a/src/lib/charm/openstack/ovn_central.py
+++ b/src/lib/charm/openstack/ovn_central.py
@@ -642,6 +642,7 @@ class BaseOVNCentralCharm(charms_openstack.charm.OpenStackCharm):
             _addrs = list(addrs or [])
             for port in ports:
                 for addr in _addrs:
+ addr = addr.replace('[', '').replace(']', '')
                     ch_ufw.modify_access(addr, port=port, proto='tcp',
                                          action='allow', prepend=True,
                                          comment=ufw_comment)