Unable to access some nextcloud directories from external network

i´m unable to access some directories and files on a nextcloud installed on synology server. this directories contain several subdirectories and files. nextcloud responds first acces to server is pending and after like 30’ responds “no files found here”
when i try to acces this files connecting directly to nexlcloud installation “192.168.x.x/nextcloud” there´s no issue
any idea where the problem may be?