Created a FreeBSD 14.2 Azure virtual machine using the D4ds_v6 instance type. Azure image used was freebsd-14_2 (14_2-release-amd64-gen2-zfs) published by thefreebsdfoundation. When I tried to change the MTU, the command froze forever: root@echenfreebsd:~ # ifconfig hn0 mtu 1520 up ^C^C^C^C^C^C^C Any further ifconfig calls would also freeze forever when attempting to print out hn0's information. This is the output of the channel sysctl after the freeze: # sysctl dev.hn.1.channel.12.br.tx.state dev.hn.1.channel.12.br.tx.state: intrcnt:39 rindex:3000 windex:3064 imask:1 psndsz:0 fvalue:1 ravail:64 wavail:520128
I should clarify that this does work on D4ds_v4 and D4ds_v5 instance types. It only stopped working on D4ds_v6, and I tested it with E4ds_v6 as well and it ran into the same issue.
I should also mention that the sysctl was from a different system, hence it being hn.1 instead of hn.0, but here is the commands that I used to get around the ifconfig command hang to print it out: # sysctl dev.hn.1.channel.12.br.tx.state # python -c "import subprocess; subprocess.Popen(['ifconfig', 'hn1', 'mtu', '1520', 'up']); exit()" # sysctl dev.hn.1.channel.12.br.tx.state