Slices stuck in closing; internal server error

1. I have a notebook that spreads 24 VMs  across 5  sites.  It tries to put nodes on sites with available resources.  But it keeps failing on WASH, which seems to have enough resources, but  then doesn’t when the slice  is submitted.  (Hussam mentioned a bug in the inter-site network setup – we are only using  unique local addresses.) But  then the slice persists in “closing” state for more than 24 hours.
2. When I asked the “Ask me  a question” bot  how to  delete the slices, it gave incorrect  answers (saying the slices would show up in my profile, for example). When I asked it for a notebook that  would delete the slice, it gave me code, but it did not work.
3. I changed WASH to  EDUKY, and then the slice got to StableOK, but failed in post boot config with an “internal server error” (OrchestratorHTTPError) in modify_slice().

What led to that was apparently an HTTP request timing out 3 times:

WARNING:urllib3.connectionpool:Retrying (Retry(total=2, connect=3, read=2, redirect=None, status=3)) after connection broken by 'ReadTimeoutError("HTTPSConnectionPool(host='orchestrator.fabric-testbed.net', port=443): Read timed out. (read timeout=30.0)")': /slices/modify/8458dcaf-3582-4786-9479-a4819757d752