Solaris 11.4.81: Why is network speed so slow?

[matimpl1]

Does anyone know why Solaris 11.4.81 has such slow networking speeds from VM to host using VirtualBox?

I tested using scp and get ~7 MB/sec on a MacOS host. I tried Debian 12 Linux using the same test and get ~75 MB/sec speed during the file transfer over the network. For comparison, I also tried VMWare Fusion and get ~17 MB/sec for the same test.

Is the wrong network adapter being advertised to Solaris? Is there some setting that must be changed?

[matimpl1]

I also validated that both scp -v tests are using the same cipher.

[matimpl1]

Changing the MTU on the NIC to 9000 (Jumbo Frames) increased Solaris transfer speed to ~60 MB/sec

[matimpl1]

This tripled my transfer rate, increasing the tcp send buffer in Solaris 11:

sudo ipadm set-prop -p send_buf=98304 tcp