How water heater leaking

Gas heater. Leaking from the cold inflow pipe where it attaches to the unit. The water is off now, but I suspect, but do not know, that the solution is fairly straight forward. I tried to tighten the fixture at that connection, but it did not move and since I absolutely did not know what I was doing, was unwilling to use anything resembling force. What kinds of things can I look for?
? What are the best and worst case scenarios? Is this something I should even think of attempting to repair myself…between the fact it uses both water and gas I am not really gung ho but if simple I absolutely wish to at least try.

It was installed on 3/4/2011, if they will help with the differential.

What type of connector? can you post a picture?

Water heaters rust out and have to be replaced–but this shouldn’t happen with one only 4 years old.

The connection is a tapered National pipe thread (Dry Lock Thread)
a leak there after 4 years is probably a corrosion issue and tightening might break fitting off inside the connector. I would,
Turn off gas,
Drain reservoir, this is a good and recommended procedure to remove sediments from heater,
Break inflow piping at a union or cut piping in a easy to access spot close to heater.
You don’t have to be a plumber to reassemble today with all the nifty quick attach fittings.
Try and remove leaky fitting.
And a couple pictures would help.
good luck

Probably corrosion. Shut off the water valve and dry off the top of the unit. Turn the water back on and if the small dimples on top where the water is connected fill up slowly, that’s what it is.

As a previous poster noted, shut off the gas, drain the unit (hook a garden hose to the valve at the base) and disconnect the water lines. Assuming it is leaking from the nipple (the short piece of pipe between the water lines and the water heater itself), you will probably need an actual pipe wrench to get it off, if the corrosion is especially bad.

If you do get the old nipple(s) off, replace them with di-electric units specifically made for this. They will cost about $10 - $15 per set, and I won’t go into the specific chemistry to keep my response short but they are critical.

Also might not be a bad idea to replace the sacrificial anode rod while your at it. It basically is an electrically weak metal that any alkalinity in your water will attack first, rather than any fittings or the inner tank itself. There are tons of how to videos on you tube for WH maintanance.