How to simultaneously connect to two different networks via WiFi access points (laptop with one WiFi card)

Question

I wish to use a laptop and simultaneously connect wirelessly to an intranet and to the Internet. Assume the subnet IP address ranges are 192.168.0.X for the network with Internet access and 10.10.0.X for the intranet. I'm running Arch Linux on a 2017 model Lenovo ThinkPad. It seems that my wireless card supports combinations. I do not fully understand all the output below, but I think it confirms that my card can function in several modes at the same time.

iw list | grep -A 2 'interface combination'
valid interface combinations:
* #{ managed } <= 1, #{ AP, P2P-client, P2P-GO } <= 1, #{ P2P-device } <= 1,
total <= 3, #channels <= 2

I used this answer to get started: https://askubuntu.com/a/488604/36661

I have verified that the following command succeeds:

iw dev wlan0 interface add wlan1 type station

After running that command, I see this interface:

4: wlan1: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1000
link/ether c6:d1:7c:2b:1a:b2 brd ff:ff:ff:ff:ff:ff

However, I am not having success connecting that interface to the second access point. First I tried the NetworkManager GUI, where I created a new wireless connection, gave it a random MAC address, assigned it to the new wlan1 virtual interface and set all the other properties as I normally would. But NetworkManager did not give me the option to connect to it.

As a second step, I tried nmcli as shown:

nmcli c up wlan1_virtual  
Error: Connection activation failed: No suitable device found for this connection.

My next step was:

ip link set dev wlan1 up
RTNETLINK answers: Device or resource busy

What should I do next?

I got one idea from this page:

documentation:iw [Linux Wireless] https://wireless.wiki.kernel.org/en/users/documentation/iw/vif

The idea is to create an ad-hoc network:

iw phy phy0 interface add ah0 type ibss
ifconfig ah0 up
iw dev ah0 ibss join AdHocNetworkName 2412

Is that the right direction?

BTW, I have read conflicting answers on this subject. The answer linked above indicates this is possible, but this one says it is not possible. But the accepted answer on that question says it is possible. So far, it seems there are more "yes, it's possible" answers. So I am forging ahead.

$ uname -a
Linux 4.18.7-arch1-1-ARCH #1 SMP PREEMPT Sun Sep 9 11:27:58 UTC 2018 x86_64 GNU/Linux

If more info is needed, I'll provide it.

Answer 1

Your interface combinations

* #{ managed } <= 1, #{ AP, P2P-client, P2P-GO } <= 1, #{ P2P-device } <= 1, 
total <= 3, #channels <= 2

clearly say "number of simultaneous managed interface must be less or equal than one". In other words, you can't add a second interface of type station (which is the same as managed).

So no, you can't use this adapter to connect to two (or more) different access points as a station. You'll need an additional adapter, or a different one that supports multiple stations.