Get aggregated data from OPenDAP ncml that requires authentication using R - r

Question

I'm trying to get TRMM data from NASA OPenDAP server using the raster package in R. Initially I had some difficulty regarding authentication, but that issue was resolved.
NASA OPenDAP server publishes TRMM 3B42_daily data as individual files, one for each day and an aggregated annual data (using ncml). So, my problem now is that, using R raster package and the authentication files .dodsrc and .netrc I can download individual NetCDF files but I can't download the aggregated data.
So, this works:
library(raster)
single_date_opendap <- 'https://disc2.gesdisc.eosdis.nasa.gov:443/opendap/TRMM_L3/TRMM_3B42_Daily.7/2002/04/3B42_Daily.20020405.7.nc4'
test <- stack(single_date_opendap, varname = 'precipitation')
This doesn't:
library(raster)
url_opendap_no_brkt <- 'https://disc2.gesdisc.eosdis.nasa.gov:443/opendap/ncml/aggregation/TRMM_3B42_Daily.7/TRMM_3B42_daily.7_Aggregation_2001.ncml'
test <- stack(url_opendap_no_brkt, varname = 'precipitation')
And gives me the error message:
Error in .local(.Object, ...) :
An error occurred while creating a virtual connection to the DAP server:
Error while reading the URL: https://disc2.gesdisc.eosdis.nasa.gov:443/openda
p/ncml/aggregation/TRMM_3B42_Daily.7/TRMM_3B42_daily.7_Aggregation_2001.ncml.
ver.
The OPeNDAP server returned the following message:
Unauthorized: Contact the server administrator.
Error in .rasterObjectFromFile(x, band = band, objecttype = "RasterLayer",
Cannot create a RasterLayer object from this file. (file does not exist)
Is it possible to get data from a OPenDAP server that publishes aggregated data?

Answer 1

After some exchange with NASA support and with Antonio's tip, found out that R raster package will not work with the aggregated datasets. But ncdf4::nc_open is able to handle it. Strange because, from what I understand, raster package calls nc_open in the background.
Anyway, this works:
library(ncdf4)
url_opendap <- 'https://disc2.gesdisc.eosdis.nasa.gov:443/opendap/ncml/aggregation/TRMM_3B42_Daily.7/TRMM_3B42_daily.7_Aggregation_2001.ncml'
trmm <- nc_open(url_opendap)
and this doesn't
library(raster)
url_opendap <- 'https://disc2.gesdisc.eosdis.nasa.gov:443/opendap/ncml/aggregation/TRMM_3B42_Daily.7/TRMM_3B42_daily.7_Aggregation_2001.ncml'
trmm <- stack(url_opendap, varname = "precipitation")