Randomizing the ports *does* cause issues though.
mIRC "reserves" 1024-5000, but it doesn't use that entire range. Some routers cannot forward ranges, but rather only single ports at a time. Users (obviously) don't add all 3976 ports in that case, sometimes they just add 5. And often in this scenario they don't update their port range in mIRC, either because they are unaware that it is needed, or expect mIRC to (correctly) take the first 5 ports and fail on the rest. Whatever the reason, we see users in #mIRC who have this setup. Randomizing ports would break the setup for these users. We've actually seen users with this exact problem of having selected randomize ports and forgetting to update the range to match their router's, so I'm fairly sure it would only happen more often if enabled by default.
