Hi, my parents just bought this vDSL modem/wireless router which looked pretty capable and cheap at about 50 euros, but the software is just atrocious. Let's just say it has a client-side check that prevents entering special characters in passwords!
There is a giant archive with the GPL sources at ftp://ftp.dlink.de/dsl/dsl-3788/driver_software/DSL-3788_sw_revb2_GPLcode.tar.gz . It seems it is using linux kernel 2.6, 32MB RAM, 16MB flash , some realtek MT751X chipset, has sources for all drivers, firmwares are included and there is a lot of interesting info in the defconfig file. I haven't tried to reproduce the build according to the readme instructions, but it seems pretty interesting.
Unfortunately I can't disassemble it or risk bricking it as I am on the other side of the world right now.
Anyone else with this device? Does it seem similar to any other supported device? Is it a lost cause? 
Thanks for your help!