IDE fails to download web resources and/or hangs on startup when using DNS Proxy

[OzFalcon]

Describe the problem

Arduino IDE 2.0.4 -> 2.3.3 fails to download web resources and or hangs on startup.
OUTPUT WINDOW

Downloading packages
arduino:arduinoOTA@1.3.0
Failed to install platform: 'arduino:avr:1.8.6'.
Error: 2 UNKNOWN: Get "http://downloads.arduino.cc/tools/arduinoOTA-1.3.0-linux_amd64.tar.bz2": dial tcp [2606:4700::6812:a15]:80: connect: network is unreachable
Downloading TFT@1.0.6
TFT@1.0.6
Failed to install library: 'Arduino_BuiltIn:1.0.0'.
Error: 13 INTERNAL: Can't download library: Get "https://downloads.arduino.cc/libraries/github.com/arduino-libraries/TFT-1.0.6.zip?query=depends": dial tcp [2606:4700::6812:b15]:443: connect: network is unreachable

To reproduce

For some reason my router/modem had reverted some default settings.

Specifically the DHCP allocated DNS servers. And the DNS Proxy option was enabled.
ie. DHCP DNS now pointed to itself and it was running a DNS Proxy.

A workaround to this problem is to manually set the DNS servers / Don't use the DNS proxy.

Expected behavior

On first run, License is agreed to then Arduino IDE starts up (Does not hang) and downloads web resources.

Arduino IDE version

2.3.3

Operating system

Linux

Operating system version

Debian 12.7

Additional context

Related

• IDE doesn't start when proxy configuration is required to access network #1438
• First run hangs if IDE can't access Internet #2042

Issue checklist

• I searched for previous reports in the issue tracker
• I verified the problem still occurs when using the latest nightly build
• My report contains all necessary details