I just post this to let you know that we too have massive problems since 7 days ago. We operate 21 networks at the moment (to collect realtime sensor data). At least half of them (and every time different ones) have problems (showing connection blocked), and even the status is shown differently on different servers. Often a restart of the pc helps to connect to hamachi network for an hour, but then is blocked again. Then it is back online for a few minutes and so on. All our hamachi client are up to date.
Another phenomenon we experienced in the last 7 days was that we are connected, we can ping the target, but we can not transmit any data over this connection. It is simply blocked, or maybe too slow.
Everything feels very unreliable and unpredictable. Last Friday, for instance, we had hamachi hell. Then at 4pm everything got back online and everything (!!) was running fine over the weekend (like it did for the last months). Then Tuesday it was all downhill again.