Limited range of your remote controls could be related to radio frequency interference that comes from something in your home or in the surrounding environment. Certain electrical devices can radiate interference; this could be almost anything that is plugged into an electrical outlet.
Please keep in mind that the device can be brand new, or can be an item that has been in use for quite a while. Also, the item may continue to function properly as far as you are able to tell. The only problem with the item may be that it has started to broadcast the interference, with no other symptoms noted.
Some devices are more likely to generate interference than others. This includes TV cable, cable amplifiers, surge protectors, fluorescent lights, battery charging devices (power tools, golf carts, etc.), anything that utilizes a timer (sprinkler systems, lights, alarm systems, etc.), and a myriad of others. If the problem seems sporadic, we can safely assume that the device responsible for the interference is only being operated during these times. Again, please keep in mind that the age of the device does not determine if it is capable of broadcasting unwanted interference. Any electrical device can be the source of the problem.
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. If the range improves, then the interference is coming from a device in the garage. If no improvement is seen follow the same procedure, this time turning off the circuit breakers to your home, with the exception of the garage and test the remote controls. If improvement is noted, turn the circuit breakers back on, one by one, until the range problem resurfaces. This will allow you to narrow down what room the problem device is in. You will have to go from there to isolate it further, by unplugging and re-plugging the items in that room.