I have got hold of some sticky picture hanger type pads and Mrs Weaver is going to stick all the modems onto the wall right near to the NTE5s. I have bought some 0.25m RJ11-RJ45 cables from run-it-direct, made up from CW1308-type twisted pair. Should neaten everything up a bit and get the modems that little bit further away from any mains of any sort.
Will try some TDK ferrites on the modems’ DC cables, for good or ill. I hear the warnings, but all I can do is try it and measure and see, maintaining due skepticism.