OK, solved my own issue
lemmy-ui bypasses the variable if it sees you running localhost 1234, it hard codes 8536
export default function getExternalHost() {
return isBrowser()
? `${window.location.hostname}${
["1234", "1235"].includes(window.location.port)
? ":8536"
: window.location.port === ""
? ""
: `:${window.location.port}`
}`
: process.env.LEMMY_UI_LEMMY_EXTERNAL_HOST || testHost;
}