How to prevent TIMEOUT for VM?

Question

I tested receiving signals to telegram from google cloud which is very simple code but everytime I tried, it automatically timed-out every 3~4 hours without any error log. If I tried to enter SSH again, it shows I cannot connect server so I need to stop& restart server.

my code is as below.

import random
import time
import telegram


#open file
file_path="1.txt"
with open(file_path, encoding='utf-8-sig') as f:
    lines=f.readlines()
lines = [line.replace('\n', ' ') for line in lines]


#telegram setting
bot_token = '5305404279:AAGEUeeR-ru42q8WIk7_44FfchmRNd4joE'
bot = telegram.Bot(token=bot_token)
chat_id = 1575861348


while True:
    ran_word = random.sample(lines, 1)
    bot.sendMessage(chat_id=chat_id, text=ran_word)
    time.sleep(20)

and my command is

nohup python3 1.py &