Comment 8 for bug 1612670

I've caught the similar error. Node is offline for nailgun after the reboot, but node is available by ssh/ping. bellow is part of nailgun-agent.log from this node:

I, [2016-12-27T09:53:39.328070 #2914] INFO -- : API URL is https://10.109.36.2:8443/api
/usr/bin/nailgun-agent:338:in `_network': undefined method `gsub' for nil:NilClass (NoMethodError)
        from /usr/bin/nailgun-agent:168:in `initialize'
        from /usr/bin/nailgun-agent:1363:in `new'
        from /usr/bin/nailgun-agent:1363:in `<main>'
at depth 0 - 18: self signed certificate

if you need env with the reproduced issue I can prepare it for you, just inform me about that