I used to work at a hotel that ran a Nomadix gateway appliance to get around guests having static IPs configured from their office environments. Without it we w

I used to work at a hotel that ran a Nomadix gateway appliance to get around guests having static IPs configured from their office environments. Without it we were sure to get a call about them being unable to connect. One year the hotel purchased another across the street and connected it via fiber. As our network infrastructure was somewhat old we used a converter on each end to take a standard patch cable from each switch and transmit the data stream over the fiber. Everything worked as expected except for one key part: computers attempting to access the guest network would never receive a DHCP-assigned IP address. Static IP addresses worked just fine. After quite a bit of packet sniffing and digging into specs I found the problem: the packet size of the initial DHCP responses from the Nomadix gateway was smaller than the minimum packet size of the converters. The fix was to switch to a different model converter that operated at layer 2 instead of layer 3 and thus didn't have the packet size minimum.