Oversized packet stat on uplink to fortigate and fortilink ports

[ScotDiGe]

I have a Fortigate 90G with 5 S148F-FPOE switches connected in a line. All the uplink ports show high Oversized packet counts. I am seeing this from the gate to switch one, 1145975344 and from switch 1 to switch 2 885605148. But all uplink ports are showing these high numbers. I am getting reports of disconnects and speed issues. I have checked all ports on all switches for CRC errors. I see a few ports, but the count is 9 or less. Fortigate is running 7.4.7 and switches are running 7.6.1. This is a recommendation on the matrix, just trying to figure out what is going on. 

[Anthony_E]

Hello,

Thank you for using the Community Forum and provide your recommendation.

Do you need any help from one of our staff member?

Regards,

[ebilcari]

The main reason for this packet counter to go up could be the MTU mismatch between nodes. Are this configurations unified, some details are covered in this article.