linux wifi work only if reboot with "sudo reboot" after restarting "/etc/init.d/networking"

I have dual boot Ubuntu 16.04 LTS with Windows 10 on a Dell computer. I have iwlwifi-7260-13.ucode as the firmware. My Ubuntu mysteriously started having wifi problems after the family got a new router. It did not detect any wireless network. Networking was on but it said ‘no network devices available‘. (look like this).

I got it to work after doing

rfkill unblock all 
sudo /etc/init.d/networking restart 
sudo reboot

The wifi works now, but stops working again if I restart the computer outside of the commandline.

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system information

This is the network information when there's no wifi:

$ sudo lshw -c network

  *-network
       description: Wireless interface
       product: Wireless 7260
       vendor: Intel Corporation
       physical id: 0
       bus info: pci@0000:06:00.0
       logical name: wlp6s0
       version: 6b
       serial: 5c:c5:d4:1d:76:9e
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress bus_master cap_list etheet physical wireless
       configuration: broadcast=yes driver=iwlwifi driverversion=4.4.0-21-generic firmware=16.242414.0 latency=0 link=no multicast=yes wireless=IEEE 802.11abgn
       resources: irq:58 memory:f7c00000-f7c01fff

$ ip addr show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1
    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: wlp6s0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq state DOWN group default qlen 1000
    link/ether 5c:c5:d4:1d:76:9e brd ff:ff:ff:ff:ff:ff

$ ifconfig -a 
lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:2740 errors:0 dropped:0 overruns:0 frame:0
          TX packets:2740 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1 
          RX bytes:202624 (202.6 KB)  TX bytes:202624 (202.6 KB)

wlp6s0    Link encap:Etheet  HWaddr 5c:c5:d4:1d:76:9e  
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

This is the network information when there is wifi:

$ sudo lshw -c network
  *-network               
       description: Wireless interface
       product: Wireless 7260
       vendor: Intel Corporation
       physical id: 0
       bus info: pci@0000:06:00.0
       logical name: wlp6s0
       version: 6b
       serial: 5c:c5:d4:1d:76:9e
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress bus_master cap_list etheet physical wireless
       configuration: broadcast=yes driver=iwlwifi driverversion=4.4.0-21-generic firmware=16.242414.0 ip=192.168.0.143 latency=0 link=yes multicast=yes wireless=IEEE 802.11abgn
       resources: irq:57 memory:f7c00000-f7c01fff

$ ip addr show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1
    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: wlp6s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 5c:c5:d4:1d:76:9e brd ff:ff:ff:ff:ff:ff
    inet 192.168.0.143/24 brd 192.168.0.255 scope global dynamic wlp6s0
       valid_lft 86248sec preferred_lft 86248sec
    inet6 fe80::6aa0:ba66:c808:535f/64 scope link 
       valid_lft forever preferred_lft forever

$ ifconfig -a 
lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:211 errors:0 dropped:0 overruns:0 frame:0
          TX packets:211 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1 
          RX bytes:15779 (15.7 KB)  TX bytes:15779 (15.7 KB)

wlp6s0    Link encap:Etheet  HWaddr 5c:c5:d4:1d:76:9e  
          inet addr:192.168.0.143  Bcast:192.168.0.255  Mask:255.255.255.0
          inet6 addr: fe80::6aa0:ba66:c808:535f/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:700 errors:0 dropped:0 overruns:0 frame:0
          TX packets:124 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:37793 (37.7 KB)  TX bytes:17856 (17.8 KB)

The biggest difference I noticed is that when there's no wifi, the computer doesn't seem to have an ip.

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I tried a bunch of things that didn't work too

• rebooting the computer
• reinstalling ubuntu from USB
• update the wireless driver from the original iso (following this blog post)

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Any insight into the problem or suggestions welcomed!

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