html URL: '%23' not converted to #

A webpage is opened if the URL contains '#'. But i get 'Page Not Found' error if the url contains '%23' instead of #.

Few months earlier, i was able to access my html page using the following link '%23'. https://www.something.com/index.html%23MyPage

however, these links are now not working. but works if %23 is changed to #. https://www.something.com/index.html#MyPage

curious, what could be the reason. Could it be something changed in the webserver? I have such links specified in many places and do not want to change if possible.

Will appreciate your help.