Our datacenter recently made a purchase order for several Catalyst 9300's with C9300-NM-2Y network modules, along with N9K-C93180YC-FX's to serve as spine switches. After deploying two 93180's (peer-linked in HA) and several 9300's with 10g SFP's, I started swapping the 10gig tranceivers for SFP-25G-SR-S's. At first the interfaces wouldn't come up. I already went through the series of hoops involved with discovering I needed to use FEC, and now the interfaces are up/up, but I'm experiencing connectivity issues with several clients.
I THINK I've traced the issue back to the uplink port-channel between the 9300 and the vpc nexus switches, mainly because when I shut one of the network module ports and force everything over one wire the issue goes away. Is FEC somehow incompatible with port-channels?
For the record I'm running 16.12.03a on the 9300's and 7.0(3)I7(8) on the two nexus peers. VPC consistency shows everything in the green.
