Could not connect to 'localhost:5006': Connection refused

[eserte]

The test suite fails on some of my smokers like this:

Output from '/usr/bin/make test':

PERL_DL_NONLAZY=1 "/opt/perl-5.42.0-RC2/bin/perl" "-MExtUtils::Command::MM" "-MTest::Harness" "-e" "undef *Test::Harness::Switches; test_harness(0, 'blib/lib', 'blib/arch')" t/*.t
2025/07/02-03:06:44 Starman::Server (type Net::Server::PreFork) starting! pid(1764865)
2025/07/02-03:06:44 Starman::Server (type Net::Server::PreFork) starting! pid(1764864)
Resolved [*]:5004 to [::]:5004, IPv6
Not including resolved host [0.0.0.0] IPv4 because it will be handled by [::] IPv6
Binding to TCP port 5004 on host :: with IPv6
Resolved [*]:5006 to [::]:5006, IPv6
Not including resolved host [0.0.0.0] IPv4 because it will be handled by [::] IPv6
2025/07/02-03:06:44 Can't connect to TCP port 5004 on :: [Invalid argument]
  at line 66 in file /opt/perl-5.42.0-RC2/lib/site_perl/5.42.0/Net/Server/Proto/TCP.pm
2025/07/02-03:06:44 Received QUIT. Running a graceful shutdown
2025/07/02-03:06:44 Worker processes cleaned up
2025/07/02-03:06:44 Server closing!
Binding to TCP port 5006 on host :: with IPv6
2025/07/02-03:06:44 Can't connect to TCP port 5006 on :: [Invalid argument]
  at line 66 in file /opt/perl-5.42.0-RC2/lib/site_perl/5.42.0/Net/Server/Proto/TCP.pm
2025/07/02-03:06:44 Received QUIT. Running a graceful shutdown
2025/07/02-03:06:44 Worker processes cleaned up
2025/07/02-03:06:44 Server closing!

#   Failed test at t/001_proxy.t line 19.
#          got: 'Could not connect to 'localhost:5006': Connection refused
# '
#     expected: 'Hello world!
# '
# Looks like you failed 1 test of 1.
t/001_proxy.t .. 
Dubious, test returned 1 (wstat 256, 0x100)
Failed 1/1 subtests