Docker Error: Could not connect to deb.debian.org (111: Connection refused)

I am on Windows 10 using Docker to create a Debian image. However, I believe there is something wrong in the Docker Desktop, Dockerfile, or Docker command.

In Docker Desktop, I have made three changes to the default configuration.

1. Under General I have turned on Expose daemon on tcp://localhost:2375 without TLS.
2. Under Resources > Proxies, I have http and https configured.
3. Under WSL Integration I have Ubuntu 18.04 turned on.

The Dockerfile that results in problems is as follows:

FROM debian:buster-slim

ENV LANG=C.UTF-8 LC_ALL=C.UTF-8

RUN apt-get update --fix-missing && \
    apt-get install -y wget && \
    apt-get clean

CMD [ "/bin/bash" ]

If it helps, this alternative Dockerfile runs without problems:

FROM debian:buster-slim

ENV LANG=C.UTF-8 LC_ALL=C.UTF-8

RUN apt-get update --fix-missing && \
    apt-get clean

CMD [ "/bin/bash" ]

The Docker command I use to build the Dockerfile is as follows:

>>> docker build simple-example

Note: Dockerfile is the only file in directory simple-example.

Attempting to build the Dockerfile with the Docker command given the Docker Desktop configuration results in the following error:

(base) C:\Users\usr1\Docker>docker build simple-example
[+] Building 25.4s (5/5) FINISHED
 => [internal] load build definition from Dockerfile                                                                                0.0s
 => => transferring dockerfile: 32B                                                                                                 0.0s
 => [internal] load .dockerignore                                                                                                   0.0s
 => => transferring context: 2B                                                                                                     0.0s
 => [internal] load metadata for docker.io/library/debian:buster-slim                                                               2.9s
 => CACHED [1/2] FROM docker.io/library/debian:buster-slim@sha256:240f770008bdc538fecc8d3fa7a32a533eac55c14cbc56a9a8a6f7d741b47e33  0.0s
 => ERROR [2/2] RUN apt-get update --fix-missing &&     apt-get install -y wget &&     apt-get clean                               22.4s
------
 > [2/2] RUN apt-get update --fix-missing &&     apt-get install -y wget &&     apt-get clean:
#5 21.80 Err:1 http://deb.debian.org/debian buster InRelease
#5 21.80   Could not connect to deb.debian.org:80 (151.101.54.132). - connect (111: Connection refused) Could not connect to deb.debian.org:80 (151.101.54.132). - connect (111: Connection refused)
#5 21.80 Err:2 http://deb.debian.org/debian buster-updates InRelease
#5 21.80   Unable to connect to deb.debian.org:http:
#5 22.28 Err:3 http://security.debian.org/debian-security buster/updates InRelease
#5 22.28   Could not connect to security.debian.org:80 (151.101.0.204). - connect (111: Connection refused) Could not connect to security.debian.org:80 (151.101.64.204). - connect (111: Connection refused) Could not connect to security.debian.org:80 (151.101.128.204). - connect (111: Connection refused) Could not connect to security.debian.org:80 (151.101.192.204). - connect (111: Connection refused)
#5 22.29 Reading package lists...
#5 22.32 W: Failed to fetch http://deb.debian.org/debian/dists/buster/InRelease  Could not connect to deb.debian.org:80 (151.101.54.132). - connect (111: Connection refused) Could not connect to deb.debian.org:80 (151.101.54.132). - connect (111: Connection refused)
#5 22.32 W: Failed to fetch http://security.debian.org/debian-security/dists/buster/updates/InRelease  Could not connect to security.debian.org:80 (151.101.0.204). - connect (111: Connection refused) Could not connect to security.debian.org:80 (151.101.64.204). - connect (111: Connection refused) Could not connect to security.debian.org:80 (151.101.128.204). - connect (111: Connection refused) Could not connect to security.debian.org:80 (151.101.192.204). - connect (111: Connection refused)
#5 22.32 W: Failed to fetch http://deb.debian.org/debian/dists/buster-updates/InRelease  Unable to connect to deb.debian.org:http:
#5 22.32 W: Some index files failed to download. They have been ignored, or old ones used instead.
#5 22.34 Reading package lists...
#5 22.35 Building dependency tree...
#5 22.35 Reading state information...
#5 22.35 E: Unable to locate package wget
------
executor failed running [/bin/sh -c apt-get update --fix-missing &&     apt-get install -y wget &&     apt-get clean]: exit code: 100

Which of these three -- Docker Desktop, Dockerfile, or Docker command -- is causing this error? What should I do to fix it?

ENV http_proxy=http:...
ENV https_proxy=http:...