I just upgraded from Ubuntu 17 to 18.04 and everything seemed to go pretty smoothly.
However, after the upgrade, there have been two (probably directly related issues). 1, the configuration application for my VPN (mullvad) no longer starts, which is not too pressing of an issue. 2, perhaps caused by some configuration originally managed by the VPN application, all my DNS queries from browsers are super slow.
I have tested from Chrome, Firefox, and Waterfox, and in all cases, it seems that DNS queries take between 5 to 5.2 seconds. I assume there is some incorrect configuration somewhere which is timing out after 5 seconds, then the browser proceeds with another configuration and gets a quick response back.
Here is a typical page load waterfall:
On the other hand, when I go to the command line and try dig, I get a speedy response:
$ dig www.disney.com
; <<>> DiG 9.11.3-1ubuntu1-Ubuntu <<>> www.disney.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 35027
;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 65494
;; QUESTION SECTION:
;www.disney.com. IN A
;; ANSWER SECTION:
www.disney.com. 255 IN CNAME matterhornsecure.edgekey.net.
matterhornsecure.edgekey.net. 743 IN CNAME e13055.e12.akamaiedge.net.
e13055.e12.akamaiedge.net. 19 IN A 23.54.221.6
;; Query time: 30 msec
;; SERVER: 127.0.0.53#53(127.0.0.53)
;; WHEN: Mon Jun 04 20:59:26 EDT 2018
;; MSG SIZE rcvd: 137
I set my DNS server to a Cloudflare DNS server, 1.1.1.1, but I'm not sure how that may be impacting this.
Here is some other information that I have seen asked about on other similar threads:
$ ifconfig
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 1000 (Local Loopback)
RX packets 11020 bytes 915775 (915.7 KB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 11020 bytes 915775 (915.7 KB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
tun0: flags=4305<UP,POINTOPOINT,RUNNING,NOARP,MULTICAST> mtu 1500
inet 10.11.0.19 netmask 255.255.0.0 destination 10.11.0.19
inet6 fdda:d0d0:cafe:1197::1011 prefixlen 64 scopeid 0x0<global>
inet6 fe80::a6e6:1fa2:8d15:cf1 prefixlen 64 scopeid 0x20<link>
unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 txqueuelen 100 (UNSPEC)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 1000 overruns 0 carrier 0 collisions 0
wlp2s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.0.7 netmask 255.255.255.0 broadcast 192.168.0.255
inet6 fe80::9b85:3e1:c0d1:d2f9 prefixlen 64 scopeid 0x20<link>
inet6 2604:2000:81c2:300::3 prefixlen 128 scopeid 0x0<global>
inet6 2604:2000:81c2:300:b765:7f68:a70b:8ebd prefixlen 64 scopeid 0x0<global>
ether 34:02:86:60:d3:30 txqueuelen 1000 (Ethernet)
RX packets 41063 bytes 49615001 (49.6 MB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 13120 bytes 2266057 (2.2 MB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
$ nmcli device show wlp2s0 | grep IP4.DNS
IP4.DNS[1]: 1.1.1.1
IP4.DNS[2]: 1.0.0.1
/etc/nsswitch.conf
?hosts: files mdns4_minimal [NOTFOUND=return] dns myhostname
tohosts: hosts: files dns myhostname
and restarting, things seem to be fixed. I'll test suspending and a few other things that seemed to cause problems before to confirm, but in the meantime, you may want to add that as an answer so I could award a bounty if continues to work correctly!