I have 2 devices connected via Ethernet to the hAp ac^2: a PC and a Raspberry Pi which I use as a media center. I stream videos from my PC to a Raspberry Pi. Note that Raspberry Pi is limited to a 100M ethernet.
I noticed an issue when streaming one of my high bitrate videos - skipped frames and buffering when the bitrate peaked at around 65-70 mbps. And the thing is - this video played perfectly fine when Raspberry Pi and PC were connected to my old router.
I tried a few things and here's what fixed this issue:
When I disable hardware offloading on the port to which the Raspberry Pi is connected OR on the port to which the PC is connected - the video plays perfectly fine without frame skips or buffering.

So, the question is - is this a bug of the new hAp ac^2? Or a feature? I use RouterOS 6.43.7.

I am just guessing, has your old router 100M port and not 1G?

I am just guessing, has your old router 100M port and not 1G?

Yes, the old router is 100M.

I vaguely recall reading something about how mixed speeds cause the switch chip to have to flush buffers before processing a new packet. It's best to put a cheap gigabit switch in front of the device to handle mixed speed devices so only 1gbps devices are connected directly.

100M, that is what I thought

Can you check with the ETH port going to the PC (stream source) set to 100M capability only (not 1G) and HW offload on again?
Would be interesting to see what that does to it.

Can you check with the ETH port going to the PC (stream source) set to 100M capability only (not 1G) and HW offload on again?

I set the port to 100M, enabled HW offload on all ports and the video plays smoothly, just like when HW offload is disabled.