After several days of flashing and trying I realised that the most stable / performance firmware for my Fon2100 is gargoyle_1.5.6. I am using it as a wireless bridge repeater
I wanted to move it to another place and I ssh into the box and performed a poweroff. When it came up it did not operate correctly, I still could ping the router but I could not SSH / open HTTP so I flashed the same firmware again, it won't came up

I am flashing always with FonFlash for Windows