@8vius Hello,
May I know do both powerline units have abnormal Led status?
You could download tpPLC Utility on your computer and wired computer to the problematic unit, and see if the unit could be detected by Utility?
https://www.tp-link.com/support/download/tl-pa4010-kit/#Utility
If the unit could not be detected at all, it could be a hardware issue on that unit.
If it could be found by Utlity, you could reset the powerline range extender on Utility and turn off the power save mode for it:
https://www.tp-link.com/support/faq/1612/
https://www.tp-link.com/support/faq/2018/