Does anyone have php ctype functions working?

Question

PHP

I'm testing the Respect/Validation php-validation library (available on the git, the most popular validation library).
There, all comparison functions are tied to the CTYPE family of functions (such as ctype_alnum, ctype_alpha, etc.). I tried to change the locale on my VDS . The result is zero. I checked if the locale is installed in Linux itself - it is not installed. Installed, now on locale -a the answer is:
setlocale(LC_ALL, 'ru_RU.utf8');

...
en_ZM.utf8
en_ZW.utf8
POSIX
<b>ru_RU
ru_RU.iso88595
ru_RU.utf8</b>

Same song, ctype function doesn't work.
But if you write it, it displays WEDNESDAY , and if you comment, it writes in English. That is, setting the locale works, so-and-so... But the ctype functions do not react. Including, for example, the strtoupper function does not work either. Any thoughts on this issue?.. PS Who what libraries do you use for validation?..
echo strftime("%A");