Vugen - Replay 'backend 404 error' when change network

Hi Everyone

I'm just recording a public accessible web page.  The script I'm recording literally we just hit the page and stop. 

When i am on my corporate network in the office, the script replays without issue.  When i go on any other network and replay the script, I get a backend-404 error when I attempt to hit the first URL.  Vugen hangs.  The page I'm hitting is accessible from both networks.  When I record the script in either network, it looks identical, however it will only replay on my office network.  I'm attaching 2 images of the replay.  Image 1 is the good run from the office network.  Image 2 is from another network.  It seems to be looking almost for some sort of authority?

The browser certificates when on the different networks have two different 'Issuer'.

If I'm on my office network, and I just browse to the page, and then go on another network the page fails to refresh.  I need to close the browser and re-open it and hit the URL again.

I've never seen this issue before.  Anyone got any ideas based on the attached images?

Many Thanks

Claire