The app works great when remote access is needed. Running on an older phone though, the delay to gain control is excruciating (up to 30 seconds each use). When toggled five or more times per day, it’s REALLY annoying.
So for local/LAN use only, would like to see the code posted for toggling outlets on/off directly (along with ports and any other info needed to make it work). Data sent instantly would make a huge improvement in usability.
The SmartThings app itself is cloud-based. It doesn’t communicate directly to the hub. It sends a message to the cloud and the cloud sends a message to the hub. This is true for all versions of the app. 
So it’s just not possible to do what you describe if you are going to include the app in the equation.
That said, there are a number of devices that are “eligible to run locally“ and some of these are handheld battery operated devices or Mains powered switches.
So it is possible to add another device which you could use to turn the outlet on and off. In this case, the remote/which would send a message to the hub and hub would send a message to the outlet. No cloud involved.
Is that something you’re interested in discussing further?
Oh, we should also ask what’s the brand and model of the outlet. That could make a difference.
As @JDRoberts pointed out, this is not possible. However, I use ActionTiles to setup different panels that are quickly accessible via a webpage. Takes a second or two to load and is much quicker than the App.
Might solve your issue.
SO you can control the outlet directly locally… you just cant w/ the any ST app. With the aeon minimote (default DTH only) conntected w/ the smart lighting app (no other app will do) to map the buttons the the device you want to control and a standard zwave/zigbee outlet (default DTH only) you can control your devices w/o going to the cloud.
List of devices that can run locally
Secondly unless you are VERY far away from the US or UK it should not take 30 seconds to process a command. If you are not in the US/UK or you have seriously crappy internet and need all your automations to be local you might want to check out Hubitat.
Thanks for all the replies! (And apologies for delayed response.)
@JDRoberts, ask me how I know this isn’t so… We have perhaps the crappiest ISP in the USA (their name rhymes with Suckeye Fable, near a city that is Spanish slang for toilet). It is their modem that disconnects several times a day and must be rebooted to restore Internet. Yes, it’s third-world service, and at ridiculous prices, because they have a monopoly.
So each time the SmartThings app is used to communicate with the outlet (to reboot the modem), there is never a Web connection, only a local/LAN one.
Writing this I just realized snooping the packets is a possibility – but still hoping for something more easily applied.
@rontalley, thanks for the ActionTiles suggestion. Since it’s web-based though, doesn’t appear it will work in this case.
@ sidjohn1, good to know there’s a hardware solution, thanks, but don’t want to invest in yet another gadget (too many already).
Pretty sure this comes down to a few data packets, maybe just a few bytes in a single packet; just need to know what data to send, and on what port.
The SmartThings mobile app always requires an internet connection. It’s Confirmed on the official supportbase, but it’s easy to check. Unplug the hub from the modem. The app will not be able to talk to it.
https://support.smartthings.com/hc/en-us/articles/209979766-Local-processing
Manual, on-demand control of a device or SmartApp through the SmartThings mobile app always requires an internet connection to the cloud and cannot be performed locally.
To tie up this loose end, have to report that I found perhaps the best solution. It is certainly the one I’m happiest with, namely flashing third-party Tasmota firmware to all my smart devices. It now takes longer to pick up a phone and get to the home screen than to tap control buttons. Response is instant.
Now deciding on MQTT arrangement, whether to run my own server (on router), or accept the default broker. But that’s only for remote control, local is still easier with a tap.
This solution won’t work for everyone because many smart devices aren’t supported. For those that are, it’s a no-brainer.
Thanks for the help here. Good community.
