Python Banner Grabber/port scanner provides uncompleted results

Question

I wrote this (below) Port Scanner/Banner Grabber that provides uncompleted results.

If I run it against metasploitable machine on Virtual Box, it returns all open ports and their banners. All seems okay!

If I run it against an online machine (kenobi from tryhackme) it returns:

[+] Scan results for:10.10.124.162

[+]22/tcp open:SSH-2.0-OpenSSH_7.2p2 Ubuntu-4ubuntu2.7

[+]21/tcp open:220 ProFTPD 1.3.5 Server (ProFTPD Default Installation) [10.10.124.162]

I know the port 80, 111 are open, but I don't understand why my code ignores them and doesn't work properly.

Generally speaking I notice that nmap provides very different result, but my aim is not to invent hot water, simply to understand and write basic programs.

#!/usr/bin/python

from socket import * 
from threading import *

print ("Basic Port Scanner and Banner Grabbing\n")

def connScan(tgtHost, tgtPort):
    try:
        sock = socket(AF_INET, SOCK_STREAM)
        sock.connect((tgtHost, tgtPort))
        banner = sock.recv(2048)
        banner = banner.decode('utf-8')
        print ("[+]" + str(tgtPort) +"/tcp open:" + banner )
    except:
        pass
    finally:
        sock.close()


def portScan(tgtHost):
    """Run the Port Scan selecting by domain name or IP"""
    try:
        tgtIP = gethostbyname(tgtHost)
    except:
        print ("Can't Resolve Target host %s" % tgtHost)
    try:
        tgtName = gethostbyaddr(tgtIP)
        print ("[+] Scan results for: " + tgtName [0])
    except:
        print ("[+] Scan results for:" + tgtIP)

    setdefaulttimeout(2)
    for tgtPort in range (1, 65535):
       # Thread launch a separate flow of instruction that running separately
        t = Thread(target=connScan, args=(tgtHost, int(tgtPort)))
        t.start()


def main():
    """ask for input"""
    tgtHost = input("Insert the host IP Target: ")
    portScan(tgtHost)



if __name__ == '__main__':
    main()