Install snapshot on Fritzbox 3390

I tried to install the snapshot on a Fritzbox 3390 and get this error using eva_ramboot.py
I hope somebody can help me.

SETENV memsize 0x07ae4000 Traceback (most recent call last): File "./eva_ramboot.py", line 40, in adam('SETENV memsize 0x%08x'%(addr)) File "./eva_ramboot.py", line 33, in adam resp = ftp.sendcmd(cmd) File "/usr/lib/python3.7/ftplib.py", line 273, in sendcmd return self.getresp() File "/usr/lib/python3.7/ftplib.py", line 246, in getresp raise error_perm(resp) ftplib.error_perm: 500 'SETENV memsize 0x07ae4000': command not understood.