Can't convert Fixnum into String (TypeError)

This program works with ruby and jruby but it does not work with iron
ruby. I get the following error:

multi-client-tcp-server.rb:29: can’t convert Fixnum into String
(TypeError)

I’m new to ruby. Can someone help me fix this so it will work with both
ruby, jruby and ironruby?

Thanks!
Siegfried

#!/usr/bin/ruby

Ruby - Socket Programming | Tutorialspoint

require ‘socket’ # Get sockets from stdlib

server = TCPServer.open(2000) # Socket to listen on port 2000
print “hello\n”
loop { # Servers run forever
Thread.start(server.accept) do |client|
client.puts(Time.now.ctime) # Send the time to the client
client.puts “Closing the connection. Bye!”
client.close # Disconnect from the client
end
}