Much thanks, George and others for the help. As well as saving my company thousands of dollars! :)

@george1421 I tested that earlier. It works.

Okay, I managed to upload a PCAP from Wireshark:

Wireshark Capture

After much frustration, I set up another Fog installation on Ubuntu that is working much better. I still get a “TFTP open timeout” but at least I can transfer TFTP in both Windows and on the Fog server.

So there’s something wrong with my CentOS install. I reinstalled it twice and followed the Wiki instructions to the T.

@george1421 Where is the output.pcap file saved?

@Sebastian-Roth Here’s the output of my iptables:

Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination

Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination

@Sebastian-Roth I disabled firewalld in CentOS.

@george1421 Edit: Misread the question.

Everything is on the same subnet. We’re on a .23 subnet. In fact all the devices I’m using for testing are plugged into the same switch.

I’ll work on getting the info you need.

@Sebastian-Roth Same error in Windows tftp test with firewall disabled. Its not an access denied so I’m fairly confident its not a firewall issue. I’m getting this on a VM and physical hardware install of CentOS 7.

Very strange. I even rebooted after the change for good measure.

@Sebastian-Roth Attached is output.

CentOS FW output.pdf