This article presents a situation where the data packet sent to the RADIUS agent is fragmented due to the Maximum Transmission Unit (MTU) settings, resulting in a failed connection.

• Troubleshooting incomplete Client - Server handshake
• RADIUS
• Response packet fragmented

The reason for packet drops in the connection between a client and a server might be a high MTU value configured on the server side.

For a connection to be established between the client and the server when authenticating through the RADIUS agent, a couple of exchanges must be made correctly.

For example,  the client will send out a " Handshake: Client Hello" request. For this the server will have to send back a " Handshake: Server hello " response. 

If any request/ response is sent but there are packet drops in the connection due to the maximum transfer unit ( MTU ) value, the connection will fail due to unresponsiveness.
 
The maximum transfer unit (MTU) specifies the maximum transmission size of an interface. A different MTU value may be specified for each interface that TCP/IP uses. The MTU is usually determined by negotiating with the lower-level driver. However, this value may be overridden.

If the connection between a client and a server is dropping due to unresponsiveness, one possible solution would be to lower the maximum transmission unit value for the server in question.