Deploying / publishing to shinyapps.io behind a corporate proxy

Hello,

I work alongside a small (3 people) data science team and we would like to deploy Shinys to others easily. Being a small firm under large corporate environment, certain software/updates can be difficult to obtain as there are many loopholes to get through.

We are a fan of ShinyApps.io and are actively considering the paid pathways to scale for many of our teams. I'd prefer this platform over other options as the number of developers is small (2) and there is not additional software needed.

Right now I am unable to publish the working app.R file. Without changing the http/https proxy setting, I get an error that it is failing to connect to shinyapps' S3 bucket (shinyapps-upload.s3.amazonaws.com) or to api.shinyapps.io directly. This is most likely due to our firms proxy/vpn as I have never faced this issue on my personal machine.

I have attempted to refer to Ian Pylvainens guide but have had no success in setting the appropriate settings to deploy.

Given the AWS backend, I specified the http/https proxy of port 80 (http_proxy), port 443 (https_proxy), 3838 Shiny Server, and 8787 RStudio Server. Using my environment variable USERDNSDOMAIN.

Examples:
Sys.setenv(http_proxy = "USERDNSDOMAIN:xxxx")
Sys.setenv(http_proxy = "user:password@USERDNSDOMAIN:xxxx")
(user and password being my firm log in credentials.)

I imagine I am probably specifying the wrong ports or my corporate proxy is refusing the in and out bound connections. I am open to any suggestions. I have an open communication line with the parent company IT, but they need to know what to approve/whitelist in order for them to proceed.

Thank you and I appreciate your time!