Hi,
Confirmed this on a 1810G-8, using the last firmware (P.2.2 at this time). This "Auto DoS" feature blocks NFS (NFSv4 in my case) : ip packets come in, but never come out from the switch, juste like a black hole.
And to notice : disabling the feature was not sufficient to make it work again. I had to do a hard factory reset (factory reset from the web gui did nothing) to make it work again.
It seems that this option is stickying somewhere in the configuration, even after disabling it !
Thanks for your post: I found it with google and it helps me to go the right track !
This really deserve a fix for a future firmware... Or remove this broken feature...
[Edit]
Just for completeness: even the first SYN packet emitted when mount the NFS share is blocked. So It must probably be about TCP flags combination or something like that