If a linear power supply could be used it would solve the problem .The problem is the smps is internal of the nvr. Thanks fo your help
Maybe, maybe not so much. Linear primary supply would be clean - but don't forget, it typically drops the supply to 48V DC (POE). Inside the NVR, more switchmode drops to 12, 5, 3.3, etc. So, might help, but don't bet on it curing all the RFI unless you could go linear with all the B+ supplies... expensive, bulky, and HOT. Also,the IP cams are have their own internal SMPS. They likely contribute as much as the NVR. I have same problem with pretty much ALL network gear. It's extremely "noisy" (RFI), and having much audio eqpmt/tuners in same room causes me many headaches. Ferrite chokes, shielded LAN cable, cleaner PS's all help; but in the end, I found the only thing that helps sometimes is distance ( 1/R^2)... or a faraday cage LoL. Unfortunately in your case, with the low freq RFI and "antenna LAN cables", getting far enough away from the noise on HF freqs is going to be difficult. But as bad as some networking equipment is, the one device that causes me more RFI than anything is
LED lighting. Some are worse than others, but NONE I have seen yet are even close to being "clean". LED PS's are notoriously noisy, and with proliferation of them now, unfortunately the noise is here to stay. I used to complain about noisy fluorescent lights... but no more.
My suggestion would be if the owner will allow replacing the LAN cables with STP (not UTP), that may help, though probably not practical. Most people won't go that route due to cost, and the stiffness of the cable vs UTP. Grounding may help, but remember RF ground is not same as eqpmt service ground (service grounds can be very noisy). May take some trial and error to locate best RF ground (I use a grd rod array at my shop, but that's not always feasible). RFI has always been a bear, but nowadays it's a grizzly with an attitude with SMPS's in everything.
Good luck