I'll say buyer beware on the Gamestar adapter. I can't recommend them at all. Mine was so poorly manufactured it wouldn't fit properly to the back of my Fat PS2 and I had to physically push and hold the thing in the entire time with my FreeHDBoot hard drive installed long enough to be able to make a Free McBoot memory card. Other than making the Free McBoot memory card that Gamestar adapter was worthless to me.Internal HDD is a must for Fat PS2s, it's easy to install FreeHDBoot if you have either FreeMCboot on a MC or a modchip, you need to get either a SATA network adapter the gamestar one (works well though no ethernet port), or modify the OEM one with a SATA adapter board, both are the same in terms of performance. Highly recommended.
Meanwhile the official Sony Network Adapter fit in perfect so I just shared roms from my Raspberry Pi 3B directly through the ethernet port, launching OPL from my Free McBoot memory card.