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I bought a USB wifi adapter with antenna (ID: 0bda:b812) for situations when i need a bigger wifi range (University...) and i need help getting it to work.

I'm on Ubuntu 18.04.2 LTS (gnome).

The adapter gets recognized, i have two wifi options to choose from and i can connect both to different networks (though they only work simultaneously. If i connect one, the other one connects aswell, strangely enough to a different network). However, when i turn off the built in wifi or disable it (ifconfig wlp4s0 down or via /etc/network/interfaces) the adapter won't connect anymore.

Furthermore i am pretty sure it doesnt work properly, since the adapter doesn't show me more wifi signals (i live in a very crowded area) nor does it give me better reception for the ones i see, compared to the built in wifi card.

I am by far no ubuntu pro and i'm pretty confused, read through dozens of threads with similar problems, tried out different drivers etc.

On my PC (18.04 gnome aswell but no built in wifi card) there was no problem.

This bothers me as well: lspci doesn't list the usb adapter but lshw shows it

~$ lspci -nnk | grep -iA2 net
04:00.0 Network controller [0280]: Intel Corporation Wireless 7260 [8086:08b2] (rev 73)
    Subsystem: Intel Corporation Wireless-N 7260 [8086:4270]
    Kernel driver in use: iwlwifi

rtl88x2 diver:

~$ dkms status
rtl88x2bu, 5.2.4.4, 4.15.0-45-generic, x86_64: installed

This is the ifconfig output:

~$ 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 3200  bytes 250504 (250.5 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 3200  bytes 250504 (250.5 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

wlp4s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.1.12  netmask 255.255.255.0  broadcast 192.168.1.255
        inet6 fe80::20ac:6f7:1c6c:c21c  prefixlen 64  scopeid 0x20<link>
        ether 0c:8b:fd:cc:88:f0  txqueuelen 1000  (Ethernet)
        RX packets 33824  bytes 37267883 (37.2 MB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 12855  bytes 2491006 (2.4 MB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

wlx000f02139821: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.1.68  netmask 255.255.255.0  broadcast 192.168.1.255
        inet6 fe80::d721:d902:76e2:387d  prefixlen 64  scopeid 0x20<link>
        ether 00:0f:02:13:98:21  txqueuelen 1000  (Ethernet)
        RX packets 809  bytes 156995 (156.9 KB)
        RX errors 0  dropped 20  overruns 0  frame 0
        TX packets 624  bytes 103764 (103.7 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

and for lshw -C network:

~$ sudo lshw -C network
[sudo] password for busch: 
  *-network                 
       description: Wireless interface
       product: Wireless 7260
       vendor: Intel Corporation
       physical id: 0
       bus info: pci@0000:04:00.0
       logical name: wlp4s0
       version: 73
       serial: 0c:8b:fd:cc:88:f0
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless
       configuration: broadcast=yes driver=iwlwifi driverversion=4.15.0-45-generic firmware=17.948900127.0 ip=192.168.1.12 latency=0 link=yes multicast=yes wireless=IEEE 802.11
       resources: irq:45 memory:f0500000-f0501fff
  *-network
       description: Wireless interface
       physical id: 2
       bus info: usb@2:1
       logical name: wlx000f02139821
       serial: 00:0f:02:13:98:21
       capabilities: ethernet physical wireless
       configuration: broadcast=yes driver=rtl88x2bu ip=192.168.1.68 multicast=yes wireless=IEEE 802.11bgn

Thanks for your help!

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You're seeing fewer networks because your built-in wifi is 802.11ac (Intel 7260), while your external wireless is 802.11n. Sparing the heavy details, 802.11ac is newer, faster and typically cards that support it are backwards compatible, but 802.11n is longer range, but struggles with speed in areas dense with networks like apartments and tightly packed neighborhoods.

It's entirely possible that the network you're trying to connect to only supports the 802.11ac standard, which would mean your external interface wouldn't be able to see it, and why you get disconnected after turning off only your internal wifi.

You'll either need to connect to an 802.11n network with the external or buy a chip that supports 802.11ac. They aren't much more expensive, but typically have an antenna that makes them bulkier to compensate for the reduced range.

  • Hi, thanks for your answer. I'm not seeing fewer, but exactly the same networks with exactly the same signal strength. While on another pc (in the same room), where the adapter works flawlessly, I see a LOT more networks, with remarkable better signal strength. As for the disconnecting: No problems on my pc, so i don't think the adapter or the networks are the problem While there might be issues with the 802.11n vs. 802.11ac protocol, i don't think that that's the major issue in this case. – 88x2bu Feb 17 '19 at 13:48
  • Sorry, misunderstood that part of your post where you said you're "not seeing more", I took it to mean you were seeing fewer. Looking over your information again, your cards seem to be successfully connecting to the same network. Try running this command before and after disabling the primary wifi: ping -I wlx000f02139821 8.8.8.8. This will force the ping command to use your USB wifi and will clarify whether or not it's actually able to communicate with it. – Minty Feb 18 '19 at 13:50

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