Thanks for your quick response.
I’m operating on a DHCP home network Class A. Router is a SKY hub address 192.168.01.
I’ve also got a Lenovo Thinkpad E530C running Ubuntu 14.04 LTS which I’m using now. I have tried this with the dongle too. The process I followed was…
Inserted dongle. Opened terminal and ifconfig revealed wlan0 Centronics and wlan1Realtek dongle. I disconnected wlan0 using the icon at the head of the display and in the terminal using sudo ifconfig wlan0 down. I then opened several webpages sequentially in Firefox, which it did, but after about the sixth page it then failed to open a page selected from my bookmarks and after some time trying reported Server Not Found. ifconfig reveals that no IP address is active and a ping of the router returned a sendmsg: No buffer space available.
The above process has the same result on my new Lenovo Z51-70 with a different onboard wi-fi card.
Incidentally, I tried the process a second time on my E530C because I couldn’t recall the ping message exactly and I was able to sequentially load c.20 pages before everything failed and I was able to verify the ping message.
I hope this helps.
PS I have recorded my desktop for one of these exercises and can provide this so that you can see my actions and terminal.