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By Windows traffic I mean RDP and file sharing, that sort of thing. VMs can ping each other, but nothing else if they are on different hosts.<br />
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There is no firewall between the two and no ACL on the LAN. The VLANs all seem to be working correctly. We can see the traffic but its getting lost some place. Looking at physical switches at the moment.
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you are using VMXNET3 interface ?
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There was a problem with physical switching after all. Thanks for the comments.
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Hello, we just migrated to distributed switches for our VMs on a VMware 6 U2 cluster. Following the upgrade, our VMs are having trouble talking to each other when they are on different hosts. They can ping each other by name, but things like Windows traffic won't go through. Move the VMs the same host and they can talk just fine. <br />
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We've been on the phone for hours with VMware support and getting nowhere. Its an odd problem as this was working before the switch migration. But now even when we move the VMs back to standard switches the problems continue. <br />
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I know that's all pretty vague, but if anyone has some insight, I'd appreciate it.
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Hello, we just migrated to distributed switches for our VMs on a VMware 6 U2 cluster. Following the upgrade, our VMs are having trouble talking to each other when they are on different hosts. They can ping each other by name, but things like Windows traffic won't go through. Move the VMs the same host and they can talk just fine. 

We've been on the phone for hours with VMware support and getting nowhere. Its an odd problem as this was working before the switch migration. But now even when we move the VMs back to standard switches the problems continue. 

I know that's all pretty vague, but if anyone has some insight, I'd appreciate it.

vSphere - Limited Traffic Between VMs on different hosts following switch migration

VMware, a software company founded in 1998,  was one of the first commercially successful companies to offer x86 virtualization. The storage company EMC purchased VMware in 1994. Dell Technologies acquired EMC in 2016. VMware’s parent company is now Dell Technologies.

VMware has many software products that run on desktops, Microsoft Windows, Linux, and macOS, which allows the virtualizing of the x86 architecture.  Its enterprise software hypervisor for servers, VMware vSphere Hypervisor (ESXi), is a bare-metal hypervisor that runs directly on the server hardware and does not require an additional underlying operating system.

VMware

Virtualization is the act of creating a virtual (rather than actual) version of something, including (but not limited to) a virtual computer hardware platform, operating system (OS), storage device, or computer network resources. Virtualization is usually the creation of a system that executes separate from the underlying hardware resources, or the creation of an entire desktop for systems located elsewhere, similar to thin clients.

Virtualization

A switch is a device that filters and forwards packets of data between LAN segments. Switches operate at the data link layer or the network layer of the Open Systems Interconnection (OSI) Reference Model and therefore support any packet protocol. LANs that use switches to join segments are called switched LANs or, in the case of Ethernet networks, switched Ethernet LANs. A hub is a connection point for devices in a network. Hubs are commonly used to connect segments of a LAN. A hub contains multiple ports; when a packet arrives at one port, it is copied to the other ports so that all segments of the LAN can see all packets.