While it’s true that using an edge driver (which requires a SmartThings hub) does allow a local connection to your LIFX bulbs, smartthings itself is still largely a cloud-based system.
Before we go too far down this path, are you aware that if the Internet is out you won’t be able to use the smartthings app at all? Even if your phone and the hub are on the same local network. Using the app always requires the smartthings cloud. They didn’t have to design it that way, but they did.
When you create a routine in the app, if it can run completely locally, it will have a little house symbol next to it. But there are quite a few things that can require the cloud even for a pre-built routine, such as using light groups.
So most people do not find smartthings to be a very satisfactory “Plan B“ for when the Internet is out.
If that was your main reason for using the edge Driver, you may want to look at other options from other systems.
Next, the person who wrote the edge Driver you are using appears to have left the community all together. They have not been seen in this forum since last July. So, if it’s the edge driver that is the problem, and there have been some reports of it not working well anymore with some other brands, you may be out of luck on that. I haven’t seen anyone else working on a similar edge Driver for LIFX yet. But why don’t you try asking in the author thread for that edge Driver, and see if anyone else is either having a similar problem or knows a workaround.
TP-Link Kasa Edge Driver (also LIFX)
I’m sorry I don’t have anything more helpful to add right now. smartthings does have an ongoing issue with marking a number of devices off-line when they are really still online, but that shouldn’t affect locally connected Wi-Fi devices. There have been some recent issues with Phillips hue bulbs being marked offline incorrectly, but those work connected to a hue bridge, and that wouldn’t be affecting you.
Anyway, try the thread about the edge Driver, and see if anyone there knows anything. Assuming you think fixing this issue would still meet your longterm purpose, given smartthings’ own cloud dependencies.