Running shiny applicaction hangs

Hello,
We run Rstudio server on our off network server and we experience the following behaviour when trying to run the simplest shiny application:

After clicking Run app RStudio hangs on 'Checking Installed packages' and after about a minute it returns an error that it cannot find packages shiny and sourcetools (I can load both packages in the RStudio R console)

When investigating the network traffic it looks like the page is issuing a POST request for unsatisfied_dependencies and is not getting the response.
I can also see on the server that rserver issues a curl request to CRAN that times out after ~minute.

Can you please help me understanding why RStudio is trying to update the packages when it is offline and how to fix this?

Also this errors appears in the console:
Warning messages:
1: In read.dcf(file = tmpf) :
cannot open compressed file '/tmp/Rtmpld08ln/file1b7187a3695c4', probable reason 'No such file or directory'
2: In read.dcf(file = tmpf) :
cannot open compressed file '/tmp/Rtmpld08ln/file1b7183e67d954', probable reason 'No such file or directory'
curl: (7) couldn't connect to host
Warning: unable to access index for repository https://mran.revolutionanalytics.com/snapshot/2016-07-01/src/contrib:
cannot open the connection
curl: (7) couldn't connect to host
Warning: unable to access index for repository https://mran.revolutionanalytics.com/snapshot/2016-07-01/src/contrib:
cannot open the connection