Let me clarify the situation here.
Until 0.3.4 any nodes booted with 0-OS were eligible for farming. This means even nodes that were not capable of processing reservation were still producing tokens.
This process was put in place to not penalize farmers that did not have access to ipv6.
In 0.3.5, the support for ipv4 only node has been rollout. Which means there were not more reason for any node to not be able to process reservation (actually provide useful capacity). Following this logic, only the node actually ready to process reservation are marked online.
@chrisvdg for you this means that if your node are marked offline there is an issue somewhere. Most probably in the network configuration of your farm. I noticed your farm going offline after the rollout of 0.3.5
And even personally asked to get in touch with your Organization to figure out what was going on I your farm. Seems the communication there was not optimal. Let’s solve that tomorrow, I’m back from holiday, we can have a look together.