I have upgraded to Ubuntu 18.04 and now my internet connection is GONE

I finally upgraded from 16.04 to 18.04 and the system does not connect to the internet anymore. LAN and WLN gets connected, but no internet. I tried all kinds of settings, what was recommended here doesn't apply, and have already wasted 4 days. What can I do?

Terminal response from pinging Google DNS (8.8.8.8):

ich@ThinkPad-Edge:~$ ping 8.8.8.8
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
64 bytes from 8.8.8.8: icmp_seq=1 ttl=115 time=28.2 ms
64 bytes from 8.8.8.8: icmp_seq=2 ttl=115 time=27.2 ms
64 bytes from 8.8.8.8: icmp_seq=3 ttl=115 time=22.5 ms
64 bytes from 8.8.8.8: icmp_seq=4 ttl=115 time=23.5 ms
64 bytes from 8.8.8.8: icmp_seq=5 ttl=115 time=22.7 ms
64 bytes from 8.8.8.8: icmp_seq=6 ttl=115 time=24.9 ms
64 bytes from 8.8.8.8: icmp_seq=7 ttl=115 time=26.7 ms
64 bytes from 8.8.8.8: icmp_seq=8 ttl=115 time=22.0 ms
64 bytes from 8.8.8.8: icmp_seq=9 ttl=115 time=22.7 ms
64 bytes from 8.8.8.8: icmp_seq=10 ttl=115 time=25.1 ms
64 bytes from 8.8.8.8: icmp_seq=11 ttl=115 time=24.8 ms
64 bytes from 8.8.8.8: icmp_seq=12 ttl=115 time=25.3 ms
64 bytes from 8.8.8.8: icmp_seq=13 ttl=115 time=25.1 ms
64 bytes from 8.8.8.8: icmp_seq=14 ttl=115 time=23.3 ms
64 bytes from 8.8.8.8: icmp_seq=15 ttl=115 time=27.5 ms

..and so on, it continues indefinitely..

ich@ThinkPad-Edge:~$ ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc fq_codel state DOWN group default qlen 1000
    link/ether 60:eb:69:d1:4d:89 brd ff:ff:ff:ff:ff:ff
3: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 8c:a9:82:2c:05:36 brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.2/24 brd 192.168.1.255 scope global dynamic noprefixroute wlan0
       valid_lft 2381sec preferred_lft 2381sec
    inet6 fe80::2b16:833c:a473:e0ec/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
ich@ThinkPad-Edge:~$ 

NEW:

ich@ThinkPad-Edge:~$ nslookup google.com
Server:     127.0.0.53
Address:    127.0.0.53#53

** server can't find google.com: SERVFAIL

Solution 1:

I had DNS problems in 18.04 as well. This is what I did to fix them.

 sudo rm -f /etc/resolv.conf
 sudo ln -s /run/systemd/resolve/resolv.conf /etc/resolv.conf

Unfortunately I do not remember the source, but likely it was a Q&A on this site.

Solution 2:

The problem was in the: /etc/NetworkManager/NetworkManager.conf file. There was a line which had to be commented out with an # (dns=dnsmasq). After a restart, the machine could connect to the internet. Thanks a lot for all your advice!