First step, read all the posts on what the disconnect tells you on the console and how & when it is updated. Disconnect is a side issue. reality is uplinks.
Like @Jeff-UK says, soooooo much detail missing - like do you actually have a device, is it working (how do you know), how often is it uplinking etc. And what is your other one, a different brand?
The other reality is that such debugging is done with a second gateway - again a different brand - seems like an imposition but if it turns out there is something wrong with your backhaul, we’d expect both devices to show disconnected, if they are both using the same sort of gateway firmware - which yes, means you need a BasicStation based gateway. And if you have a Packet Forwarder based gateway, you need two.
If this was WiFi that wasn’t allowing all your devices to connect to the internet then you’d have to get a second router or access point, so this is not a LW thing, it’s an RF thing.