I'm not sure where to go next with this, hoping someone can offer advice...
This is a fresh install of vCenter 5.5 and an existing ESXi 5.5 server. I see my ESXi host and all details in the web console, but it shows up as "not responding". I can successfully disconnect/reconnect but every time, 60-90 seconds after successful reconnect it goes back to "not responding".
Is there anything else I can test or do to isolate what could be causing this? I'm happy to provide any needed additional details.
Are you saying that the ESXi host are reported as disconnected only in the vSphere Web Client whereas the C# client does not report any disconnect?
I would first configure vCenter alarms to send notifications when there is a host disconnect, this will help isolate issues between ESXi/vCenter and C#/Web Client. A host "not responding" indicates that the ESXi host is unable to send/receive heartbeats to vCenter and if I am not correct is UDP port 902. I understand that you have checked networking already but you can ask your network team to check the firewall for TCP/UDP port 902.
In addition to the above, also monitor if there are any tasks that are being initiated on the ESXi host that may cause this disconnect, for e.g. taking snapshots.
Hope this helps !!
The best way to troubleshooting the issue is vpxa and hostd logs on problem ESXi host and Web Client logs.
Please also check out Windows event logs if Web Client is installed on a Windows server.
BTW, you say Web Client has problem but vSphere Client is fine, I would say you may not able to notice the disconnect/reconnect on vSphere Client if it's flapping very fast. ARP conflic or IP conflict also can cause similar problem.
I'm having a simmilar issue, VCVA 5.5, several hosts, many show as (not responding) using the web client,
but all of them have normal operations as evidenced by using the fat client.
In one case, the problem went away by restarting the web client server, but that has not done the magic in this setup.
I'm lost here...