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Connecting Client/Server program outside of LAN with Python

I am trying to create a chess game between two different computers that are not in the same LAN. I am having trouble connecting the two via a TCP connection (UDP would probably be sufficient as well if the packets are arriving, but ideally TCP).
I am new to a lot of networking and am unaware of many different tools that may be useful and I am also in university and therefore don't have control over the router to update firewall rules. What can I do to work around the router firewall to connect the two devices.
I am primarily using the Python socket library at the moment to implement the connection.
Any information about how I can send messages between the two computers outside of a LAN would be very useful. Thank you for your help!
I have ensured that the client side is using the public IP of the server and the server is using "" for its socket host. I also checked that the connection was working when utilizing a LAN without issue. I included a batch file that enables the specific port used for the game at the beginning of runtime and disables it at the end of the program. If I am not mistaken, that only impacts the computer's firewall rules not the router's. I have looked into receive the packets through port 80 and redirecting it to my specific program, but was unsuccesful in finding a solution of that type.

If the server is behind a router/firewall you'll have to use some sort of hole punching method to create the connection. STUN is one of the most common, though I've never actually used it in a Python program so I don't know what Python implementations are out there.

Socket over internet Python Embedded

I have an embedded system on which I can connect to internet. This embedded system must send sensor data to PC client.
I put a socket client using python on my PC. I put a socket server ( using C++ language on the embedded system because you can only use C++ ).
I can succesfully connect from my PC to the embedded system using the sockets and send and recieve whatever I want.
Now, the problem is I use local IP to connect to the system and both of them must be connected to the same Wifi router.
In the real application, I won't know where the embedded system is in the world. I need to get to it through internet, because it will be connectet to internet through 4g.
My question is, how can I connect to it through internet, if the embedded system is connected to internet using 4G?
Thank you

Realistically in typical situations, neither a PC nor an embedded device hanging off a 4g modem will likely have (or should be allowed) to have externally routable addresses.
What this practically means is that you need to bounce your traffic through a mutually visible relay in the cloud.
One very common way of doing that for IoT devices (which is basically to say, connected embedded devices) is to use MQTT. You'll find support in one form or another for most computing platforms with any sort of IP networking capability.
Of course there are many other schemes, too - you can do something with a RESTful API, or websockets (perhaps as an alternate mode of an MQTT broker), or various proprietary IoT solutions offered by the big cloud platforms.
It's also going to be really key that you wrap the traffic in SSL, so you'll need support for that in your embedded device, too. And you'll have to think about which CA certs you package, and what you do about time given its formal requirement as an input to SSL validation.

I think your problem is more easily solved if you reverse the roles of your embedded system and PC. If you are communicating to a device using IP protocols across cellular networks, it is much easier to have the device connect to a server on the PC rather than the other way around. Some networks/cellular modems do not allow server sockets and in any case, the IP address is usually dynamically allocated and therefore difficult to know. By having the device connect to a server, it "knows" the domain name (or IP address) and port to which it should make the connection. You just have to make sure that there is indeed a server program running at that host bound to some agreed upon port number. You can wake up the device to form the connection based on a number of criteria, e.g. time or amount of collected data, etc.

i am sending commands through serial port in python but they are sent multiple times instead of one

i am sending some commands having particular response serially using com port..the commands are kept in a file..i am reading each command through the file line by line and sending it serially over the com port..but when i am seeing it from the receiver end using Magic Terminal(Software)..i found that each command is going multiple times..which i am sending only one time..i have made a code in pycharm..and in the console i am seeing that command is going only once but from the uart receiving end the story is something else..i am stuck with this problem..i have maintain the same baudrate and everything but not able to diagnose the issue..
github link for the code is: https://github.com/AkshatPant06/Akshat-Pant/blob/master/cmd%20list
def recvResponse():
ser.write(serial.to_bytes(intCmd))
time.sleep(1)
data_recv=ser.read(2)
return data_recv
this i have used to receive the 2 byte response..

There seems to be nothing wrong with your code. At least to the extent I could reproduce, it only sends the command once (I tried your function after setting up my serial port in loopback).
I cannot say for sure but it might be that the terminal you're using has two windows, one for input and another one for output and somehow you're getting confused with what is in and out of your port.
One easy way to deal with this kind of issue is to use a sniffer on your port. You can do that combining com0com and Termite on Windows, as I recently explained here.
As you can see there is only one window on this terminal, and after setting up the forwarding you'll everything that comes in and out of your port. That should make it easier to see what your code is writing and reading.
To give you a conventional scenario to apply the sniffer trick you can refer to the following screenshot:
In this case, we have two real serial ports on a computer. On the first (COM9) we are running a Modbus server (you can imagine it as a bunch of memory addresses, each of one storing a 16-bit number). On COM10 we have a client that is sending queries asking for the contents of the first 10 addresses (called registers using the Modbus terminology). In a general use case, we have those ports linked with a cable, so we know (theoretically) that the client on COM10 is sending a data frame asking for those ten registers and the server on COM9 is answering with the numbers stored on those registers. But we are only able to see the contents on the server (left side of the picture) and what the client is receiving (right). What we don't see is what is traveling on the bus (yeah, we know what it is, but we don't know exactly how the Modbus protocol looks like on the inside).
If we want to tap on the bus to see what is being sent and received on each side we can create a couple of virtual ports with com0com and a port forwarding connection with Termite, something like the following screenshot:
Now we have moved our Modbus server to one of the virtual serial ports (COM4 in this case). After installing com0com we got (by default, but you can change names or add more port pairs, of course) a pair of forwarded ports (COM4<-->COM5). Now, if we want to see what is circulating through the ports we open Termite (bottom-right side of the picture) and set up another port forwarding scheme, in this case from virtual port COM5 to the real port COM9.
Finally (and exactly the same as before we were sniffing), we have COM9 connected together with COM10 with a cable. But now we are able to see all data going to and fro on the bus (all those HEX values you see on Termite displayed with the green/blue font).
As you can see, this will offer something similar to what you can do with more professional tools.

Exchange internal ip blindly using python

I would like to share my internal IP between two devices on a network (using python 3).
Let's say I have my phone, and my computer. Both connected to the same network. I need to run a client and server script to connect the two but in order to do that, my phone (client) needs the ip of the computer (server).
The IP of the computer changes all the time (school wifi, nothing I can do about it) and even so I would like this to work instantly when connected to a new router without having to manually enter the IP.
One more thing, due to the huge amounts of devices on the network, mapping every device and finding the computer name to get the IP will take too long for its purpose.

Please use DNS for the purpose, or assign static addresses to your devices, and use the defined static addresses in your scripts.

In case anyone was wondering. I take this question as unsolvable, but, in order to solve my issue, I have set my computer to upload its internal IP to a server each time it connects to a new network. My phone then reads the server.

How can I block Internet access for a certain IP in my local network in python?

I am trying to find a way to block a certain Mac address / Internal IP from accessing the internet (Blocking a device in the LAN to WAN) in python.
This option is available in every modern router in every home but mine is kinda old and doesn't have that feature.
I have a basic knowledge in networking stuff and consider myself an Advanced-Beginner in python, so I'm up for the challenge but still need your help.
*Of course with the option to enable the internet again for that device

I know I am kinda late now but... You can't necessarily block internet access to a machine like you would do in your router's config.
What you CAN do is implement something like an ARP Spoofer. Basically what you would do in a Man-in-the-Middle attack.
You send a malicious ARP packet to poison the target's ARP table. Making it believe your machine is the router/default gateway. That way you can intercept every packet being transmitted by the target. You can then choose if you want to router them or not.
If you choose not to forward the packets, the connection to the internet is cut off.
If you want to forward the packets to the actual router (in order to allow the target to access the internet) you must enable IP Forwarding on your machine.
You can do this by running echo 1 >> /proc/sys/net/ipv4/ip_forward on Linux or changing the Registry Key in HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\IPEnableRouter on Windows ('1' forwards the packets, '0' doesn't). By default IP forwarding is set to 0.
Remember you must resend the malicious ARP packet every couple of seconds as the ARP tables get updated quite frequently. This means you don't necessarily have to change the IP Forwarding configuration on your machine. After a minute or less of exiting the script the target's ARP table will go back to normal, giving them access to the internet again.
Here are some python modules you might want to take a look at:
Scapy (Packet Manipulation Tool)
winreg (Windows Registry)

Blocking of traffic has to happen inside the router. If the router does not have this feature, consider to replace it with a new one.