Firewall blocks attachment images - any way around this? VB 3.8.4
 

I did a search and found a lot of threads reporting this issue, but not a solid response from Jelsoft on how to mitigate it (most just talked about how the user might be logged on as a guest, etc, but that isn't the case)

I've recently started using attachments for certain threads. For most users this works fine, but for some users they are unable to view the attachments (they show up as a broken image).

I am a root admin, and am able to see the images just fine from my home machine, but on my work network, the images are indeed broken. I've reproduced this issue on one other machine that has antivirus software running (somewhere totally outside of work).

As I can't access my work firewall I understand there might be no way around this, but would like to know the mitigation steps for other users who can - and/or it would be nice to know why this is happening (do firewalls view it as xss? Or why would this be happening?). Is there anything I can do in my vbulletin itself that would fix this? Such as using a relative path, etc? (I have no idea how the attachments are coded, that's just a made up example)

thanks in advance.