vowifi issue maybe due to change/lowering in MSS size?

  • 29 July 2022
  • 1 reactie
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My previous company is experiencing some problems with vowifi.

We have a TCP MSS size adjustment on our company edge routers to a value of 1360.
I believe the MTU is kept standard at 1500.


Could this adjustment of MSS size potentially cause this problem or do we have to search elsewhere for this problem?


I read somewhere on this forum the following: On your firewall, you must open ports 500 and 4500 on your firewall to allow UDP traffic. and set the MTU to 1500 bytes for IPv4 and 1800 bytes for IPv6.


But it doesn’t say anythnig about the MSS size being adjusted.



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Difference Between MSS and MTU in Computer Networking - GeeksforGeeks

MSS = MTU - 40 (IP header + TCP header)

Technical Tip: Setting TCP MSS value - Fortinet Community

By default it will be 40 bytes less than MTU. So if a PC's MTU has by default 1500 bytes it will send a MSS of 1460 bytes.