That is one possibility or could be a TV satellite dish, ham radio,
police scanner, TV cable not grounded properly, cell phone tower, or
another garage door opener (would need to be fairly close like in same
garage or multi-family type buildings). The other possibility is that
something in the receiver is defective & no longer sending a very
strong signal.

How old is the unit? If parts are still under warranty you may want to
change the receiver first. Or to rule out any interference from inside
your home turn off all breakers except for the one that powers the
garage door opener to see if the problem goes away.

Outside interference is constantly becoming a problem & sometimes it
will also simply disappear in a couple of days & sometimes it becomes
permanent. There have been many installations where we have had to
install an external receiver on a different frequency to get proper
distance. However those may not be compatible w/ your built-in car
remotes.

We have some whole sub-divisions in our area where the range has been
severely limited for years. The more radio waves that are in the air
the greater the chance of interference becomes.
Doordoc
www.DoorsAndOpeners.com

wrote:
snip
Outside interference is constantly becoming a problem & sometimes it
will also simply disappear in a couple of days & sometimes it becomes
permanent.
snip

This is certainly true. Once in awhile, one or both of my garage doors
will start going up and down all by itself. I cure it by unplugging the
power to the motor unit for a few minutes. But it's not clear whether
that reset the receiver or the an interference source just left the
neighborhood.