how to make http proxy setting as "automatically detect"?

i am connecting through my mobile connection,which don't have proxy setting
i can access internet in browser using  "automatically detect setting",i get
error when trying below

source("http://bioconductor.org/biocLite.R")

Error in file(file, "r", encoding = encoding) : 
  cannot open the connection
In addition: Warning message:
In file(file, "r", encoding = encoding) :
  InternetOpenUrl failed: '???L
M??w?%'

i set proxy as none by

Sys.setenv(no_proxy="") 
Sys.getenv("http_proxy")

[1] ""

is there any way to tell R about "auto detect setting" for mobile 
connections

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