Question details:

As a security device I have an RJ45 coupler in the cable between my computer and internet modem, and I only couple the two cable segments when I need to be online. Needless to say eventually the cable connector breaks and I have to replace the cable segment. I could really use a simple inexpensive inline on/off switch to replace the coupler between the two cable segments, but can't find such a thing.

Answer:

I guess you need something like this. You can try it to buy from there are search on the Internet other available places to buy.