nginx-proxy-manager: Let's Encrypt HTTP challenge renewal fails with timeout

Describe the bug Since about two months, certbot renewal of letsencypt certificates fails. This is persistent through several versions of NPM now and none of the exisiting issues such as fixing dns inside docker have solved the issue.

Nginx Proxy Manager Version 2.9.10

To Reproduce Steps to reproduce the behavior:

1. Start docker
2. wait for renewal of soon expiring certificates
3. Check docker logs
4. Errors out with:

[11/2/2021] [7:07:02 PM] [Migrate  ] › ℹ  info      Current database version: 20210423103500
[11/2/2021] [7:07:02 PM] [Setup    ] › ℹ  info      Logrotate Timer initialized
[11/2/2021] [7:07:02 PM] [Setup    ] › ℹ  info      Logrotate completed.
[11/2/2021] [7:07:02 PM] [IP Ranges] › ℹ  info      Fetching IP Ranges from online services...
[11/2/2021] [7:07:02 PM] [IP Ranges] › ℹ  info      Fetching https://ip-ranges.amazonaws.com/ip-ranges.json
[11/2/2021] [7:07:06 PM] [IP Ranges] › ℹ  info      Fetching https://www.cloudflare.com/ips-v4
[11/2/2021] [7:07:11 PM] [IP Ranges] › ℹ  info      Fetching https://www.cloudflare.com/ips-v6
[11/2/2021] [7:07:15 PM] [SSL      ] › ℹ  info      Let's Encrypt Renewal Timer initialized
[11/2/2021] [7:07:15 PM] [SSL      ] › ℹ  info      Renewing SSL certs close to expiry...
[11/2/2021] [7:07:15 PM] [IP Ranges] › ℹ  info      IP Ranges Renewal Timer initialized
[11/2/2021] [7:07:15 PM] [Global   ] › ℹ  info      Backend PID 249 listening on port 3000 ...
`QueryBuilder#allowEager` method is deprecated. You should use `allowGraph` instead. `allowEager` method will be removed in 3.0
`QueryBuilder#eager` method is deprecated. You should use the `withGraphFetched` method instead. `eager` method will be removed in 3.0
QueryBuilder#omit is deprecated. This method will be removed in version 3.0
Model#$omit is deprected and will be removed in 3.0.
[11/2/2021] [7:09:05 PM] [SSL      ] › ✖  error     Error: Command failed: certbot renew --non-interactive --quiet --config "/etc/letsencrypt.ini" --preferred-challenges "dns,http" --disable-hook-validation
Failed to renew certificate npm-4 with error: Some challenges have failed.
Failed to renew certificate npm-5 with error: Some challenges have failed.
All renewals failed. The following certificates could not be renewed:
  /etc/letsencrypt/live/npm-4/fullchain.pem (failure)
  /etc/letsencrypt/live/npm-5/fullchain.pem (failure)
2 renew failure(s), 0 parse failure(s)

    at ChildProcess.exithandler (node:child_process:397:12)
    at ChildProcess.emit (node:events:390:28)
    at maybeClose (node:internal/child_process:1064:16)
    at Process.ChildProcess._handle.onexit (node:internal/child_process:301:5)

Expected behavior Certbot will automatically renew expiring certificates

Operating System Linux 5.13.0-arm64 #1 SMP PREEMPT Debian 5.13.15-202109101456~buster (2021-09-10) aarch64 GNU/Linux

Additional context I use the following ports, as my NPM is installed alongside Nextcloudpi, which by default occupies default HTTP(s) ports 80/443. Externally, ports 443 and 80 point towards 40443 and 8080, respectively. However, this was not a problem earlier (prior to ~August/September 2021).

version: '3'
services:
  app:
    image: 'jc21/nginx-proxy-manager:latest'
    restart: always
    ports:
      - '8080:80'
      - '8081:81'
      - '40443:443'
...