Configure apt-get to work through corp internet proxy

["Wilkinson, Matthew" <MatthewWilkinson@alliantenergy.com>]

Hello Debian users,

I'm experimenting with Debian in an enterprise environment. We have a corp. Internet proxy which downloads and scans files prior to passing the files onto the client. 

With Debian this seems to be a problem for APT. I am able to run 'apt-get update' and that seems to work OK, however when I try to actually run 'apt-get upgrade' on Debian 10 it tries for a few seconds to download a patch for: 'linux-image-4.19.0-5-amd64', which is 47.6MB. It tries and gives up fairly quickly. 

       # apt-get upgrade
       Reading package lists... Done
       Building dependency tree
       Reading state information... Done
       Calculating upgrade... Done
       The following packages will be upgraded:
         linux-image-4.19.0-5-amd64
       1 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
       Need to get 47.6 MB of archives.
       After this operation, 3,072 B disk space will be freed.
       Do you want to continue? [Y/n] y
       Get:1 http://cdn-fastly.deb.debian.org/debian-security buster/updates/main amd64 linux-image-4.19.0-5-amd64 amd64 4.19.37-5+deb10u2 [47.6 MB]
       Err:1 http://cdn-fastly.deb.debian.org/debian-security buster/updates/main amd64 linux-image-4.19.0-5-amd64 amd64 4.19.37-5+deb10u2
         Undetermined Error [IP: x.x.x.x]
E: Failed to fetch http://cdn-fastly.deb.debian.org/debian-security/pool/updates/main/l/linux-signed-amd64/linux-image-4.19.0-5-amd64_4.19.37-5+deb10u2_amd64.deb  Undetermined Error [IP: x.x.x.x]
       E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?

I have tried to search Google to find a way to significantly increase the timeout that APT has or the number of retries without any success, but I fear I may be doing it wrong. Here is my apt.conf:

       # cat /etc/apt/apt.conf
       Acquire::http::Proxy "http://proxy.domain.tld:80";;
       Acquire::http::Timeout "999";
       Acquire::https::Timeout "999";
       APT::Acquire::Retries "5";

Anyone have any experience with forcing Debian's APT to try very hard and for a long time while doing downloads/upgrades? If it matters I'm running Debian 10 AMD64 on VMware vSphere.

Thanks,