Incorrect Adguard upstream DNS?

[qvanphong]

• [v] I've read the FAQ and my problem isn't described there.
• [v] I've also searched through the existing issues, and my problem hasn't been brought up

Describe the issue
After the setting is finish. The Adguard home which accessible from adguard.yourdomain.xxx is pointing to 127.0.0.1:8053, which ad block not working.
I checked through the container adguard-unbound-doh which show they are listening on port 53 (there are something that listening on port 9053 too).

Logs of adguard-unbound-doh container

 [2023-10-23 07:41:43] [NOTICE] dnscrypt-proxy 2.1.1
2023/10/23 07:41:43.463413 [info] AdGuard Home, version v0.107.16
2023/10/23 07:41:43.486134 [error] creating dhcpv4 srv: dhcpv4: <nil> is not an IP address
2023/10/23 07:41:43.521329 [info] Initializing auth module: /opt/adguardhome/work/data/sessions.db
2023/10/23 07:41:43.525311 [info] auth: initialized.  users:0  sessions:0
2023/10/23 07:41:43.527312 [info] web: initializing
2023/10/23 07:41:43.534209 [info] DNS cache is enabled
2023/10/23 07:41:43.535238 [info] MaxGoroutines is set to 300
2023/10/23 07:41:43.535894 [info] AdGuard Home is available at the following addresses:
2023/10/23 07:41:43.539679 [info] Go to http://127.0.0.1:3000
2023/10/23 07:41:43.540020 [info] Go to http://10.8.2.2:3000
[2023-10-23 07:41:43] [NOTICE] Network connectivity detected
[2023-10-23 07:41:43] [NOTICE] Now listening to 127.0.0.1:9053 [UDP]
[2023-10-23 07:41:43] [NOTICE] Now listening to 127.0.0.1:9053 [TCP]
2023/10/23 07:41:43.581880 [info] Starting the DNS proxy server
2023/10/23 07:41:43.583087 [info] Ratelimit is enabled and set to 20 rps
2023/10/23 07:41:43.583346 [info] The server is configured to refuse ANY requests
2023/10/23 07:41:43.583423 [info] MaxGoroutines is set to 300
2023/10/23 07:41:43.583492 [info] Creating the UDP server socket
2023/10/23 07:41:43.584881 [info] Listening to udp://[::]:53
2023/10/23 07:41:43.584990 [info] Creating a TCP server socket
2023/10/23 07:41:43.585124 [info] Listening to tcp://[::]:53
2023/10/23 07:41:43.585476 [info] Entering the UDP listener loop on [::]:53
2023/10/23 07:41:43.586694 [info] Entering the tcp listener loop on [::]:53
[2023-10-23 07:41:45] [NOTICE] Source [public-resolvers] loaded
[2023-10-23 07:41:45] [NOTICE] Firefox workaround initialized
[2023-10-23 07:41:45] [NOTICE] [cloudflare] OK (DoH) - rtt: 8ms
[2023-10-23 07:41:45] [NOTICE] Server with the lowest initial latency: cloudflare (rtt: 8ms)
[2023-10-23 07:41:45] [NOTICE] dnscrypt-proxy is ready - live servers: 1
[2023-10-23 07:47:13] [NOTICE] dnscrypt-proxy 2.1.1
2023/10/23 07:47:13.589943 [info] AdGuard Home, version v0.107.16
2023/10/23 07:47:13.622418 [error] creating dhcpv4 srv: dhcpv4: <nil> is not an IP address
2023/10/23 07:47:13.645965 [info] Initializing auth module: /opt/adguardhome/work/data/sessions.db
2023/10/23 07:47:13.649059 [info] auth: initialized.  users:0  sessions:0
2023/10/23 07:47:13.649079 [info] web: initializing
2023/10/23 07:47:13.650367 [info] DNS cache is enabled
2023/10/23 07:47:13.650375 [info] MaxGoroutines is set to 300
2023/10/23 07:47:13.651071 [info] AdGuard Home is available at the following addresses:
2023/10/23 07:47:13.692547 [info] Starting the DNS proxy server
2023/10/23 07:47:13.692564 [info] Ratelimit is enabled and set to 20 rps
2023/10/23 07:47:13.692567 [info] The server is configured to refuse ANY requests
2023/10/23 07:47:13.692570 [info] MaxGoroutines is set to 300
2023/10/23 07:47:13.692749 [info] Creating the UDP server socket
[2023-10-23 07:47:13] [NOTICE] Network connectivity detected
2023/10/23 07:47:13.694590 [info] Listening to udp://[::]:53
2023/10/23 07:47:13.694596 [info] Creating a TCP server socket
[2023-10-23 07:47:13] [NOTICE] Now listening to 127.0.0.1:9053 [UDP]
[2023-10-23 07:47:13] [NOTICE] Now listening to 127.0.0.1:9053 [TCP]
2023/10/23 07:47:13.697198 [info] Listening to tcp://[::]:53
2023/10/23 07:47:13.697514 [info] Entering the UDP listener loop on [::]:53
2023/10/23 07:47:13.697869 [info] Entering the tcp listener loop on [::]:53
[2023-10-23 07:47:13] [NOTICE] Source [public-resolvers] loaded
[2023-10-23 07:47:13] [NOTICE] Firefox workaround initialized
2023/10/23 07:47:13.737713 [info] Go to http://127.0.0.1:3000
2023/10/23 07:47:13.737727 [info] Go to http://10.8.2.2:3000
[2023-10-23 07:47:13] [NOTICE] [cloudflare] OK (DoH) - rtt: 9ms
[2023-10-23 07:47:13] [NOTICE] Server with the lowest initial latency: cloudflare (rtt: 9ms)

Solution

• Go to Adguard Home through adguard.yourdomain.com
• Setting -> DNS Setting -> Change 127.0.0.1:8053 in "Upstream DNS servers" to 127.0.0.1:53 or choose the Adguard DNS Provider from this list
• Click "Test Upstream" to confirm that it works then click "Save"

FYI

• The default value of "Upstream DNS servers" is 127.0.0.1:8053, If you click on "Test Upstream" it will alert us about fail to test.
• I changed to port 9053 which showed on the log, it also fail.

Environment:

• Client OS: Linux
• VPS OS: Ubuntu 20.04
• VPS Provider: Digital Ocean

[qvanphong]

Update:
After few minutes, the port 53 is not accessible anymore, and the 8053 is successfully in test upstream??? Straight