DNS configuration problems, wifi.radio.dns properties can't be manually set

[jepler]

CircuitPython version

Adafruit CircuitPython 9.2.0-beta.1 on 2024-10-11; Adafruit MagTag with ESP32S2

Code/REPL

>>> wifi.radio.addresses
('10.0.3.28',)
>>> wifi.radio.dns
('FD5F:3F5C:FE50::1',)
>>> wifi.radio.ipv4_dns
>>> wifi.radio.ipv4_dns = ipaddress.ip_address("1.1.1.1")
>>> wifi.radio.ipv4_dns
>>> wifi.radio.dns = ('1.1.1.1',)
>>> wifi.radio.dns
('FD5F:3F5C:FE50::1',)

Behavior

I was trying to reproduce #9711 and I grabbed this recently updated magtag. I found that I couldn't resolve ANY hostnames to addresses.

It is set up with CIRCUITPY_WIFI_SSID and _PASSWORD.

The radio gets an ipv4 address but an ipv6 DNS server, which already seems pretty broken. and the DNS server can't be reset by assigning the dns or ipv4_dns properties either.

Description

If I enable ipv6 autoconfiguration, I get working DNS using the IPv6 DNS server address

Additional information

No response

[jepler]

Actually it appears that the address is being continuously overwritten ...

>>> wifi.radio.dns = ('10.0.2.76',); wifi.radio.dns
('10.0.2.76',)
>>> # Wait 10 seconds
>>> wifi.radio.dns
('FD5F:3F5C:FE50::1',)

This is due to the IPv6 "neighbor discovery"; my router sends a RNDSS (recursive DNS server) announcement. lwip unconditionally overwrites the DNS server list with this. IPv6 neighbor discovery cannot be runtime disabled, so it runs even if IPv6 DHCP is not enabled and the device has no IPv6 address assigned.