To make this as simple as possible, download this file This is the old version 4.10.1303.0
With Kodi file manager go to storage/.kodi/cdm folder and rename “libwidevinecdm.so” to libwidevinecdm.so.new. Then copy downloaded one to this folder.
Do the same in “storage/.kodi/userdata/addon_data/script.module.inputstreamhelper/cdm” folder.
Reboot your box and try how it works.