server expert report export hang up

i have software hosted on linode server. Exist 2 reports when are exported appears the loading bar infitely and report is never exported. These reports are working fine on localhost (probably because local pc have more resource than vps) but anyways are not complex report.... on linode server probably will take more time to export but should work. Developer says on production server is not apperaing any log related to help him to solve the issue. Previous server admin try to fix this issue and he change db indexes and works fine on testing server but when was put the same indexes on production server the same issue is happening so i am looking someone to help me to debug this in order to have reports working fine