Ubuntu 16.04 cannot resolve dns - connection timed out; no servers could be reached

[marcosti]

Hi,

I'm running Ubuntu 16.04 (Linux pine64 3.10.104-2-pine64-longsleep) for a few days on my Pine64 2GB. What I notice is that after a reboot DNS works fine, but after sometime DNS is no longer able to resolve. 

When DNS fails I get a message like:

nslookup www.google.com
;; connection timed out; no servers could be reached

However, if I reboot the Pine64 DNS works like a charm. 

I've got a fixed IP defined in /etc/network/interfaces.d/eth0
auto eth0
#iface eth0 inet dhcp
iface eth0 inet static
address 192.168.1.158
netmask 255.255.255.0
gateway 192.168.1.1
dns-nameservers 8.8.8.8


Which works because ifconfig shows the following:

eth0      Link encap:Ethernet  HWaddr 4a:7c:01:2a:0d:57
          inet addr:192.168.1.158  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::487c:1ff:fe2a:d57/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:172911 errors:0 dropped:9 overruns:0 frame:0
          TX packets:84150 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:28673200 (28.6 MB)  TX bytes:26435938 (26.4 MB)
          Interrupt:114


ip route shows the following:
default via 192.168.1.1 dev eth0 onlink
192.168.1.0/24 dev eth0  proto kernel  scope link  src 192.168.1.158

Does anybody have a suggestion where I should look for the rootcause/solution?