I have one Google Compute Engine instance and I want to open udp port 53 on it. I have added some firewall rules(as in this link) to allow traffic, but it does not seem to solve the problem. (Only worked when I tried to open TCP port 8080 for a web server)
VPC firewall rules

I have also tried updating the iptable rules manually:

sudo iptables -A INPUT -p udp -m udp --dport 53 -j ACCEPT && sudo iptables -A INPUT -m state --state NEW -p tcp --dport 8080 -j ACCEPT && sudo netfilter-persistent save

The DNS server I would like to open on port 53 on the VM:

from scapy.layers.dns import DNS, DNSRR
import socket

simple_udp = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, proto=socket.IPPROTO_UDP)
simple_udp.bind(('0.0.0.0', 53))

domains = {
    b"proiect-retele-reguli-stricte.chickenkiller.com.": "34.118.118.214",
}

print(domains.keys())

try:
    while True:
        request, adresa_sursa = simple_udp.recvfrom(65535)
        # converitm payload-ul in pachet scapy
        packet = DNS(request)
        dns = packet.getlayer(DNS)
        if dns is not None and dns.opcode == 0: # dns QUERY
            print ("got: ")
            print (packet.summary())

            print(dns.qd.qname)
            if dns.qd.qname in domains.keys():
                dns_answer = DNSRR(  # DNS Reply
                rrname=dns.qd.qname, # for question
                ttl=330,             # DNS entry Time to Live
                type="A",
                rclass="IN",
                rdata=domains[dns.qd.qname])     
                dns_response = DNS(
                                id = packet[DNS].id, # DNS replies must have the same ID as requests
                                qr = 1,              # 1 for response, 0 for query 
                                aa = 0,              # Authoritative Answer
                                rcode = 0,           
                                qd = packet.qd,     
                                an = dns_answer)    
                print('response:')
                print (dns_response.summary())
                simple_udp.sendto(bytes(dns_response), adresa_sursa)
except KeyboardInterrupt:
    simple_udp.close()

Every time I am running this on my local machine I always get “No response received”

from scapy.all import *

def dns_query(target_ip, dns_server):
    dns_query = IP(dst=dns_server)/UDP(dport=53)/DNS(rd=1, qd=DNSQR(qname=target_ip))

    responses, _ = sr(dns_query, verbose=0, retry=2, timeout=5)
    if responses:
        for pkt in responses:
            if pkt[DNS].an:
                print(pkt.summary())
            else:
                print("No response received.")
    else:
        print("No response received.")

dns_query("proiect-retele--stricte.chickenkiller.com.", "34.118.23.175") # vm external ip

Is there anything that is blocking traffic on udp:53 or am doing something incorrectly?