I have a setup where the CRS328 powers a few APs, and the uplink port (ether24) which shows many Rx overflow errors. Most APs run on gigabit links, except maybe two 100M ones. Total traffic through the switch is like 200-300 Mbps most of the time, so the Rx overflows are difficult to explain (no, not using any 10Gb SFP+ yet).
Enabling flow control on ether24 and on the switch connected there resolves the problem, the other switch counters show both Tx and Rx pause frames, but CRS328 counters still show 0 Tx/Rx pause frames.
Things get much worse when (due to bad cable or RJ45 plug) wired link to one of the APs went from 1G to 10M. This stopped everything, until flow control was disabled (by power-cycling the other switch where the change that enabled flow control was not permanently saved yet - as it was impossible to even connect to the CRS328 with winbox through the same uplink port).
So, does this relatively new hardware still suffer from the Head-Of-Line blocking issue? I thought it was mostly an issue with old switches.
And, there is a bug (still in 6.43.8 ) that Tx/Rx pause frames are not counted (even though the other end clearly shows them).
EDIT: RB1100AH running 6.42.10 also shows Tx/Rx pause frame counters as 0, even though flow control works (Rx overflow counter on the CRS328 connected to the RB1100AH stopped increasing after it was enabled, both Tx/Rx directions on both sides set to "auto"). DELL PowerConnect 5324 switch shows increasing counters correctly.