Caldazar

Greetings, I recently took over a server from a friend, where it ran fine. On my PC, which is superior on all specs in comparison, people are getting one-way lag. That is, in the console I can see that the server receives the data from the players instantly(less than a second delay). Yet it takes an additional 20 seconds before they can see it on their console. This is not the case for me if I log in through the server pc. Some are also a lot slower than others, yet the server receives all messages instantly per console overview. It is also running on an SSD, has 6gig ram and my upload capacity was at 5%. Do anyof you have any idea?