Question marks instead of national letters in console

I have Netgear Stora MS2000 (which uses a modified version of Red Hat) and have strange font issues while connecting by SSH. Note that this occurs both when connecting by PuTTY from Windows and by performing ssh from Mac console.

When I use some Polish letter and type ls it is displayed as two question marks. However, when I try to autocomplete the file name it displays correctly. This is illustrated in the following picture:

Tried to change TERM and LANG variables to different values but without any luck.

I also noticed wrong display of mc, this may (or may not) be related to the same issue:

Any ideas what should I change?

The screens where made from PuTTY but it looks the same from Mac terminal.