joannesalfa wrote:Is there a way to create virtual SSID with WEP pass from this repeater?
A WDS system cannot change encryption on the fly. You could try a universally bridged wireless network (i.e. a repeater without WDS) but I'm not quite sure how to set that up with OpenWRT.
The easiest solution, is to either downgrade the encryption of the Wi-Fi network to WEP, or to purchase newer cameras which support WPA2.
If this is not an option, then if your OpenWRT router has two radio devices (such as 2.4 GHz and 5 GHz) available, then you can configure things so that one of the radios acts as a client in the Wi-Fi network hosted by the Arris router, while the other one hosts a new Wi-Fi SSID that uses WEP. Your cameras then connect to the latter.
To make things easy from the network perspective, you could configure the OpenWRT router so that the "client Wi-Fi" is bridged to the second Wi-Fi, and thus it "extends" the first wireless network in a sense, although in reality the network medium is switched in-between, and the wireless networks themselves have nothing in common. Both networks use same IP addresses, DHCP servers, DNS servers and so on, making network management somewhat simpler.
If your OpenWRT router has only a single radio device, then what I suggested above might also be possible, but it requires that both the WPA2-AP and the new WEP-AP to use the same wireless channel (the one radio in the OpenWRT router can tune only to a single channel at a time) and it will probably reduce the effective throughput of the wireless channel to a crawl, rendering the network unusable if your cameras generate a lot of data onto the network.
There might also be other complications getting the two APs operational on the same channel as well. I've never done something like that so I can't anticipate them or help you out if you run into problems.