Please upgrade to mitmproxy mitmproxy 7.0.2 (4 August 2021) https://github.com/mitmproxy/mitmproxy/blob/main/CHANGELOG.md This may fix broken port see https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=257073
Maintainer created https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=258500