SolrCloud looses connection to Zookeeper but stays down?

[Henrik Ossipoff Hansen <ho...@entertainment-trading.com>]

We are slowly starting to move from a Master/slave setup into SolrCloud, and with the addition some new functionality on our site, we decided to give it a go in production (with a very minimal setup so far).

We are experiencing that our nodes looses connection to ZK during the night according to the log:

02:17:33 WARN OverseerCollectionProcessor Overseer cannot talk to ZK
02:17:33 WARN Overseer Solr cannot talk to ZK,​ exiting Overseer main queue loop

The node is listed as down in the cloud window in Solr admin. However, as I'm speaking, it seems to be able to speak with ZK just fine; I can just fine update configurations from ZK to SolrCloud nodes - but the nodes are still listed as down. Everything seems to work.

Is this a known bug, that they are still listed as down even though they're up and active? We're running 4.4.0.