After spending some nerve cells, I managed to get UDPBD running. Here's what I learned:
-UDPBD is very "picky" about formatting, even if you're running a Windows server. To maximize success, you should format the drive to GUID (not MBR) and exFat using a Gparted Live USB.
For some reason, the UDPBD program poorly identifies formatted disks via Windows 10, it recognize, but simply does not work with this
-If you want to get UDPBD running on the A5-V11, first make sure that USB drive working in UDPBD Server Linux/Windows
-Micro USB has power pass-through to the USB-A port. I checked with a multimeter, and it's 0 ohms between the Micro USB 5V and USB-A 5V. The router doesn't use any additional 5V regulation, so don't reinvent the wheel. If your 700 mAh HDD runs off Single USB, that's perfectly sufficient.
-I saw a power consumption comparison after bootup on a foreign forum:
230mA with WiFi on
160mA with WiFi off
110mA with WiFi off and Unused 4 LAN off
It said that the Ralink chip uses power for the four unsoldered 4 LAN ports, even when they're not in use. They need to be disabled to reduce heat generation.In this thread above there were script on how to disable this.
-Sometimes the router doesn't turn on on the first try. The router exhibits the following behavior: its red and blue LEDs glow dimly. To fix this, modify the board by removing 4 SMDs and soldering in a MAX809TTR chip. I added a photo under the spoiler showing how to install it.
-As mentioned earlier, the router is overheating and needs a CPU heatsink. After the work is done, I plan to remove the connectors, hide inside PS2 and place it on the PS2 shielding using a thermal pad. I think this will be enough to dissipate heat.
These are the results I was able to achieve:
A5-V11 Stock Firmware SMB: 1.1 mb/s
A5-V11 OpenWRT SMB: 2.2mb/s
A5-V11 OpenWRT UDPBD: 4.1mb/s
Unfortunately, this isn't the most impressive speed of UDPBD. When running it on a PC, I got 7.1mb/s. But keep in mind that the maximum linear speed of the PS2 DVD drive in laboratory conditions is 4.5 MB/s
Once I've polished the process, I'll dump the flash drive and write more detailed instructions. Huge thanks to
@moahdib for breathing new life into this device; we couldn't have done it without you.