If the bad opener suddenly has good range again then the other unit in your garage is causing rf interference.
Garage door opener signal weak.
Troubleshooting a lost signal on your remote is as easy as resetting the old signal on the motor opener and equipping your transmitters with new signals.
To isolate potential sources of interference turn the circuit breaker off to the garage and plug the garage door opener into an extension cord from another room.
Multiple garage door opener troubleshooting test start by unplugging the opener that has good range powering down this unit.
Clip the remote control onto a sun visor in the vehicle instead of a metal ash tray or metal dash board that can.
On most of the newer garage door openers there is a little led light next to the learn button on the back of the opener.
Before installing the extension kit move any metallic objects that may obstruct the signal between the remote control.
Any electrical device can be the source of the problem.
Test the opener that has the poor range.
It flashes because it s hearing the radio signal from your transmitter remote.
If you watch that little light while you push the button on your remote you will see it flash.
The remotes work by electronically sending a signal to the motor inside your garage allowing you to open and close the door.
Modern garage door openers are essentially small radios that operate at about 315mh and a few feet of extra distance can affect the signal.