Thanks for reaching out, I'm sorry to hear you're having issues when disabling SSL v3.0 and RC4 support on your Octopus server. Can I please confirm if you have performed a full server reboot after making the change to disable SSL v3.0 and RC4?
Thanks for keeping in touch, In this case I believe one possible solution could be to disable the SSLv3 and RC4 change using an application called IIS Crypto
IIS Crypto is a third party application used to enable or disable protocols, ciphers, hashes and key exchange algorithms on Windows and it might be able to assist you. Please ensure that you backup your Octopus server including the Windows registry before making any changes though.
I am interested to know if this has been helpful for you.