I encounter a problem when I'm trying to use a Ubuntu laptop computer to connect to two identical WiFi AP in the same time.
On that laptop there are two WiFi NICs, one is embedded (say, Wifi-A) and the other is an Asus USB-N13 ProN USB dongle (say, Wifi-B).
I can successfully connect to and control (well, actually these AP are Sony cameras, A6000) these two AP (say, AP-A & AP-B) through these two WiFi NICs, provided only one AP is used a time.
For example, either using Wifi-A to control AP-A or AP-B, or using Wifi-B to control AP-A or AP-B, will work. I think this proves both the AP and WiFi NICs hardware function correctly, and any combination of WiFi NIC and AP works fine, too.
However, it will be different if I try to connect and control both AP in the same time. Simultaneous connections to both AP are OK (though sometimes not very smooth), but controlling them is not.
Here is a list of the experiment steps:
Wifi-B connects to AP-B. Wifi-B gets IP address 192.168.122.166
Wifi-A connects to AP-A. Wifi-A gets IP address 192.168.122.165
Send M-SEARCH request to Wifi-A and get response from AP-A. Then get Device Description XML file successfully. (This is a standard SSDP procedure which Sony A6000 supports)
Send M-SEARCH request to Wifi-B and never get response
As I'm not familiar with network management, I'm wondering if such configuration (One laptop + two WiFi NICs + two identical AP) is not valid because these AP will both use IP address 192.168.122.1 (there seems to be no option to change this IP address) for themselves? If this configuration is invalid, is there any way (e.g., modify some setting of Ubuntu) to fix or workaround?
As I got no response from the Stackoverflow for Sony after posting this question for few days, I desperately turn to Serverfault as this issue might actually be an networking one that Sony guys are not familiar.
I'll appreciate if any one could comment on this issue.
@Burgi, Here is my answers to your questions:
Why can't the cameras connect to the same network?
I guess the reason is because Sony originally intended to enable these camera users to control their camera from a mobile device like mobile phone or tablet, instead of computer like PC, Mac, etc. To wirelessly connect a mobile phone to a camera even when there is no WiFi AP (e.g., in the field), it would be feasible solution to make the camera an AP which allows a mobile device to connect to.
In case you are interested in the detail, here you can find the freely downloadable Sony Camera Remote API beta SDK: https://developer.sony.com/downloads/camera-file/sony-camera-remote-api-beta-sdk/
Are they physically a large distance apart so that the signals don't overlap?
No. In fact, these two cameras are side-by-side with each other
Is there an existing wifi or LAN they can connect to?
WiFi or LAN do exist in the place these cameras are located. However, as they don't have RJ45 port, LAN won't help. And, even under some mode they can connect to a WiFi AP so that can access Internet to download program (yes, they are basically computers running FedoraCore!), such mode doesn't provide the function I need: Accept and execute commands from a computer. Such function is only available when they act as a WiFi AP.
Why two NICs?
Because, as far as I know, one WiFi NIC can connect to only one AP. It takes two NICs to connect to two APs. Of course I'll be more than happy if I can use only one NIC to connect to two APs. Is this possible??
After doing experiments for many days, I'm sure this symptom is caused by the IP address conflict (both of them are 192.168.122.1) of these two A6000.
As I can't find a way to change them, my optimal solution under such configuration (one laptop + two Wifi adapter + two A6000) is to make use of Linux Network Namespaces. Moving Wifi-B to a new Network Namespace does solve this issue, because every Network Namespace has its own network stack. Now I can freely access both of these A6000 from my laptop.
I hope this answer is helpful to anyone who encounters a similar problem.