The spec is 100 meters or about 330 feet so you're well under that. What id of cable? Is it solid copper or CCA (copper clad aluminum)? CCA is a no-no in the video surveillance world. Did you terminate the cable in 568Aor 568B on both ends or is it a pre-made cable, if so by who?
40 meters should be a piece of cake. The official limit is 100m / 328 feet. I've got a few runs close to that with no problems. As in the post above, this all assumes you have good cable and correct terminations.
Thanks for your reply. The cable was installed and terminated (568A) by a local electrician. I have connected other devices (non POE) and have no issues.
I'd still lean toward a bad termination on one end or the other. Is the camera outside and is the RJ outside properly sealed and was dielectric grease used on the connector? You can also try bringing the camera in and test using a known good cable. That will help eliminate the camera as the problem.
I'll assume the camera is outside. Even if it is under an eve or otherwise protected moisture can occur in the RJ connection due to condensation from heating and cooling. It doesn't take much which is why I mentioned dielectric grease and proper sealing. I still think it's a bad, flaky, termination on one of the connectors especially given that it tests fine on the bench. If you can get to the cable, itself, have a look at the markings and make sure it is copper and not marked CCA. DId your electrician supply the cable?
I vote for a bad termination. They can and do go bad even though they look perfect. Been there, done that. Then the question is, which end do you cut first... Terminating cables yourself is not difficult, just a little learning curve, paying someone to come re-terminate two ends would pay for the crimping tool set.
Especially if it sat unprotected in the elements between when one camera was taken down and another put up!
My one neighbor that takes his sweet time to do anything (mowing a quarter acre lot yard is a 3-day ordeal lol), he took his old cameras down one day, and several months later got around to installing the new cams and only half of them worked because the connectors corroded being exposed for that amount of time.
I just use a dab to protect the pins on both the male and female connector, but you can fill the female too. Personal [reference I guess. Way less of a mess with just a dab though and it seems to be very effective, IMHO.