A Microsoft file hosting and synchronization service.
i used this a temp workaround, https://answers.microsoft.com/en-us/msoffice/forum/all/onedrive-folders-shared-with-me-for-years-are-now/941db6bf-96fa-4821-bc71-f4c0ab7a2b63
but note i had to reboot my pc before creating another network folder, but once i had added about 4 shared folders it a decent workaround until microsoft fix it