Can disabling IPv6 in Proxifier resolve the 'Proxy Connection Failed - IPv6' error?

Yes, disabling IPv6 in Proxifier is a common workaround. Go to 'Profile' -> 'Proxy Servers' -> Select your proxy -> 'Advanced' and uncheck 'Use IPv6'. This forces Proxifier to use IPv4, which may resolve the error if the issue lies specifically with IPv6 connectivity. However, this means you won't benefit from IPv6's potential speed and security advantages if your proxy supports it.