Alt Gr not working under antiX terminal

I have an antix installation which has this problem, when I'm trying to use Alt Gr + 2, the terminal just outputs the number 2, leaving me without the @ special character. This happens the same to the other special characters requiring Alt Gr or Ctl Alt. When I do a dpkg-reconfigure keyboard-configuration and restart the computer, I'm able to get the special characters, but randomly the problem gets back. With setupcon I can get it back but that's a little bit weird because when I power off or reboot the machine several times again the problem comes back. Another strange thing is that when I open the X server on the machine the keyboard is able to output the special characters without any configuration. So this looks like a terminal problem, could somebody give me some help please ? Antix is based on Debian so I can try to use some solution related to Debian. Contents of /etc/default/keyboard:

XKBMODEL="pc105" 
XKBLAYOUT="es" 
XKBVARIANT="winkeys" XKBOPTIONS="lv3:ralt_switch,terminate:ctrl_alt_bksp" 
BACKSPACE="guess"