Upgrading from 6.41.4 to 6.42 all the way through 6.43.2 results in an unusable LAN.

It's possible to SSH to the CRS-125 with no issues in latency, but all other LAN connections are unusable. Intra LAN streaming video doesn't work, and while it is possible to SSH to another client on the network, it's like typing through a 300 baud modem, or worse. Which is strange because SSH or any connections to the CRS are fine. ICMP ping between clients is actually normal, though. A speedtest to the internet results in something like .01 Mb/sec.

I tried a few versions of routeros from 6.42.1 all the way to 6.43.2 and they all have the same behavior. Firmware has been upgraded as well.

6.43.2 - bad (slow lan, works to ssh to crs)
6.42.9 - bad (slow lan, works to ssh to crs)
6.42.1 - bad (slow lan, works to ssh to crs)
6.41.4 - good
6.41.3 - good

Fasttrack is enabled. I'm not sure where to start and unfortunately sending a supout is not an option.