On my workstation (=non admin rights), I’ve tried to replace Portable Dropbox by Syncthing to access my current work folder at home.
No wrapper (SyncTrayzor, SyncthingGTK) could be installed, of course. So I just launch the bare Syncthing executable.
Issue: neither does it see to any of the other repos, nor could it be seen by them.
Portable SyncTrayzor was the first I tried. To no avail (it requires .Net Framework 4.5, which I cannot install).
I don’t think SyncthingGTK has a portable version but I gave the normal version a go. It requires python27.DLL, which I cannot install either.
If you had a device working successfully outside your home network, it could be, that your company firewall is blocking outgoing traffic. Dropbox used the default HTTPS port (443) which is “never” blocked. But syncthing uses other ports, which might be blocked.
If you have no HTTP(S) Server running at home (on that machine, or which is accessibly from the internet) you can change the address for the sync protocol in the main syncthing settings.
I changed mine to listen to the default 0.0.0.0:22000 plus the one which is needed to get through my company firewall, resulting (in your case) in 0.0.0.0:22000, 0.0.0.0:433
You should disable UPnP and set up the port forwarding in your home router manually, as UPnP will probably not map 443 externally.
I don’t know if global discovery will work with both adresses. I entered my second port + dyndns address in the device config on the node at work.