Problems connecting to python Socket on a vps (for a chat program)

Hello,
I've a **Debian vps** and I'm trying to make a **chat program**. I've the following code running on the server (vps):

import socket
host, port = "51.77.66.55",9999
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind((host, port))
s.listen(5)
client,addr = s.accept()
print("Connection received from :",addr)
while True:
msg = client.recv(1024)
print(str(msg,"utf-8"))
and the following running on my machine:

import socket
host, port = "51.77.66.55",9999
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((host, port))
while True:
msg = input("--> ")
s.send(bytes(msg,"utf-8"))
This code is just a simple test but I can't seem to make it work.
I get the error : **ConnectionRefusedError: [Errno 111] Connection refused**
I'm quite certain this is not a problem with my code because it works fine with 127.0.0.1 on my machine.
The **iptables** of my vps is **open for all the ports**.

Chain INPUT (policy ACCEPT)
target prot opt source destination

Chain FORWARD (policy ACCEPT)
target prot opt source destination

Chain OUTPUT (policy ACCEPT)
target prot opt source destination

**What am I missing here ??**
**Is there another kind of firewall I'm not aware of? Is OVH blocking certain ports?**

thanks a lot

ps : 51.77.66.55 is not the actual ip of my vps but I checked, it not an ip problem either. I also tried with other ports like 80 and got the same results.