Ran into a weird issue with our fleet of 1570R quantum sparks. Eventually resolved it. But no idea *why* this resolves it.
Background: We deploy 1570R gateways to all remote office/sites of a certain size. Fleet is around 20 now. Hardly have a single issue with any of them - they're usually very reliable. Recently we began deploying them to cellular-only sites. i.e. No fibre-optic / physical carrier infrastructure was available. It all looked really good initially running off 4G/LTE. Deployment was simple / elegant without many of the headaches I would usually run into with ruggedised cellular modems.
Then we had the first PC client try to use the route via the new gateway. Every connection perfect. Except all web-related traffic. Very weird. Anything Teams (falling back to HTTPS) or HTTP/HTTPS web-browsing traffic was blocked. When you analyse the flow of traffic a little further, it looks very much like a TCP out-of-state type scenario between the client and the internal web-proxy back at head office. Bearing in mind that we'd been using these gateways everywhere across our network and it was only after we tried using its' cellular capability that we ran into this problem, the whole scenario was rather strange.
Getting even stranger, we were able to "fix" the problem briefly by performing an "ipconfig /release && ipconfig /renew" on the client. This is almost a workaround, but is fairly ugly to inflict on a poor user. As soon as they reboot their client PC, the issue reoccurs.
At long last (in desperation!) I began messing with random settings on the gateway. Under /Other/More Settings/ there's a check-box for something called "Enable Legacy URL Filtering". When you check this particular box and deploy policy, the issue appears to be completely resolved.
So my question is therefore: What does that do exactly? It's been quite a few weeks trying to figure this one out, so I've had time to become very curious about the answer!
