ConnectionAbortedError: [WinError 10053] using socket and rsa encryption with pycryptodome

Question

server.py

from socket import *
from threading import *
from Crypto.PublicKey import RSA
from Crypto.Cipher import PKCS1_OAEP

length = 4096
key = RSA.generate(2048)
public_key = key.publickey()

host = '127.0.0.1'
port = int(input("Enter a port: "))

server = socket(AF_INET, SOCK_STREAM)
server.bind((host,port))
server.listen()
print(f"Server running on {host}:{port}")

clients = []
usernames = []
usrs_keys = {}

def broadcast(msg, _client,username):
    for client in clients:
        if client != _client:
            public_client_key = usrs_keys[username]
            encryptor = PKCS1_OAEP.new(public_client_key)
            encrypt_msg = encryptor.encrypt(msg)
            client.send(encrypt_msg)

        
def handle_messages(client,address):
    while True:
        index = clients.index(client)
        username = usernames[index]
        try:
            msg = client.recv(length)
            encryptor = PKCS1_OAEP.new(key)
            decrypt_msg = encryptor.decrypt(msg)

            broadcast(decrypt_msg, client,username)
        except:
            broadcast(f"ChatBot: {username} disconnected".encode('utf-8'),client,username)
            clients.remove(client)
            usernames.remove(username)
            client.close()
            print(f"{username} disconnected from {str(address)}")
            break

def recive_conn():
    while True:
        global usrs_keys
        client, address = server.accept()
        client.send("@username!".encode('utf-8'))
        username = client.recv(length).decode('utf-8')
        client.send("key!".encode('utf-8'))
        usr_public_key = RSA.importKey(client.recv(length), passphrase=None) 
        usrs_keys[username] = usr_public_key
        client.send(key.publickey().exportKey(format='PEM', passphrase=None, pkcs=1))

        clients.append(client)
        usernames.append(username)

        print(f"{username} connected from {str(address)}")

        msg = f'ChatBot: {username} joined the chat.'.encode('utf-8')
        broadcast(msg, client,username)
        client.send("Successful connection".encode('utf-8'))

        thread = Thread(target=handle_messages, args=(client,address))
        thread.start()

recive_conn()

client.py

from socket import *
from threading import *
from Crypto.PublicKey import RSA
from Crypto.Cipher import PKCS1_OAEP

ACCEPTED_CHARS = ('a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z','1','2','3','4','5','6','7','8','9','0','_','.')
ctl = 0
length = 4096

while True:
    user = input("Enter your username: ")
    for i in user:
        if i not in ACCEPTED_CHARS:
            ctl += 1
    if ctl != 0:
        print('Error: invalid character(s)')
    else:
        break

host = input("Enter an ip: ")
while True:
    try:
        port = int(input("Enter a port: "))
        break
    except:
        print("Error: Invalid port")

key = RSA.generate(2048)
server_key = None

client = socket(AF_INET, SOCK_STREAM)
client.connect((host,port))

def handle_keys():
    try:
        if client.recv(length).decode('utf-8') == "@username!":
                client.send(user.encode('utf-8'))
        elif client.recv(length).decode('utf-8') == 'key!':
                global server_key
                client.send(key.publickey().exportKey(format='PEM', passphrase=None, pkcs=1))
                server_key = RSA.importKey(client.recv(length), passphrase=None)
    except:
        print("An unexpected error has occurred!")
        ssl_client.close()


def recive_msg():
    while True:
        try:
            msg = client.recv(length)
            encryptor = PKCS1_OAEP.new(key)
            decrypt_msg = encryptor.decrypt(msg)
            print('@'+decrypt_msg.decode('utf-8'))
        except:
            print("An unexpected error has occurred!")
            client.close()
            break

def write_msg():
    while True:
        entry = input('$')
        msg = f'{user}: {entry}'
        encryptor = PKCS1_OAEP.new(server_key)
        encrypt_msg = encryptor.encrypt(msg.encode('utf-8'))
        client.send(encrypt_msg.encode('utf-8'))

recv_thread = Thread(target=recive_msg)
recv_thread.start()

write_thread = Thread(target=write_msg)
write_thread.start()

Everything works fine but when the client connects to the server the server gives an error but I don't understand what is wrong this is the error it gives me

Traceback (most recent call last):
  File "C:\Users\delaf\OneDrive\Escritorio\armadillo\server.py", line 77, in <module>
    recive_conn()
  File "C:\Users\delaf\OneDrive\Escritorio\armadillo\server.py", line 61, in recive_conn
    usr_public_key = RSA.importKey(ssl_client.recv(length), passphrase=None)
ConnectionAbortedError: [WinError 10053] An established connection was aborted by the software in your host machine

I removed some comments so the lines that the error says may not match but there is all the code

I don't know if the "length" variable is too small or if it can't be any value, I also don't know if it affects the port I use for the tests, which is 42069 (it's obvious why) or if I have to configure the firewall to open that port (although I don't think so because I'm working locally). sorry if my english is not very good or there are translation errors but i speak spanish