[NuGet.org Bug][IPv6]: Unable to load the service index for source https://api.nuget.org/v3/index.json

[kevinoid]

Impact

I'm unable to use NuGet.org

Describe the bug

Running dotnet tool search foo (or any other command which attempts to use the NuGet API) fails with the error

Unhandled exception: Unable to load the service index for source https://api.nuget.org/v3/index.json.

This has been occurring intermittently for me for about a week.

Repro Steps

On a machine with IPv6 connectivity, run dotnet tool search foo.

Expected Behavior

The command would complete without error.

Screenshots

No response

Additional Context and logs

I believe the issue is due to being unable to connect to api.nuget.org using IPv6. curl -6 https://api.nuget.org/v3/index.json produces the error

curl: (28) Failed to connect to api.nuget.org port 443 after 134768 ms: Could not connect to server

Wireshark reveals that TCP SYN packets sent to port 443 of either 2607:fa18:0:90::a646:9289 or 2607:fa18:0:90::a646:928a receive no response (which are the addresses in the DNS response I receive):

dig api.nuget.org AAAA output

; <<>> DiG 9.20.15-2-Debian <<>> api.nuget.org AAAA
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 2793
;; flags: qr rd ra; QUERY: 1, ANSWER: 5, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;api.nuget.org.			IN	AAAA

;; ANSWER SECTION:
api.nuget.org.		290	IN	CNAME	nugetapiprod.trafficmanager.net.
nugetapiprod.trafficmanager.net. 12 IN	CNAME	api.nuget.org.edgesuite.net.
api.nuget.org.edgesuite.net. 11169 IN	CNAME	a2043.dscr.akamai.net.
a2043.dscr.akamai.net.	110	IN	AAAA	2607:fa18:0:90::a646:9289
a2043.dscr.akamai.net.	110	IN	AAAA	2607:fa18:0:90::a646:928a

;; Query time: 4 msec
;; SERVER: 192.168.21.1#53(192.168.21.1) (UDP)
;; WHEN: Mon Nov 03 10:51:26 MST 2025
;; MSG SIZE  rcvd: 213

mtr indicates that packets are lost after 2001:1900::3:143:

Start: 2025-11-03T10:54:26-0700
HOST: kevinolos                                                                     Loss%   Snt   Last   Avg  Best  Wrst StDev
  1.|-- 2607:24c0:2300:9fc5::1                                                         0.0%   100    1.6   1.3   0.9   3.3   0.3
  2.|-- 2607:24c0:2000::4                                                              0.0%   100    2.6   2.6   1.7  31.8   3.3
  3.|-- 2604-9440-2301-0003-0000-0000-0000-0001.utopiafiber.com (2604:9440:2301:3::1)  0.0%   100    3.0   2.2   1.7   3.3   0.3
  4.|-- et-3-0-27.edge8.Denver1.Level3.net (2001:1900:2100:31::3329)                   0.0%   100   48.9  20.2  16.2  48.9   6.7
  5.|-- 2001:1900::3:143                                                               0.0%   100   27.7  29.9  26.7  97.6   9.8
  6.|-- ???                                                                           100.0   100    0.0   0.0   0.0   0.0   0.0

Perhaps this is an issue with Akamai or Level3? In either case, this seemed like a reasonable place to start, in case other NuGet API users are experiencing this issue. Any advice or assistance would be greatly appreciated.