So I put a new network switch in the Great Hall, which left me with a surplus-to-requirements 5-port switch. "I know", I thought, "I will use this one instead of the one that's already in the Estate Office as, being not made of cheese, the mass of the cables plugged into it will not try to drag it from its position atop FatBoy (4TB NAS) into the dark and hellish maw of the spaghetti monster under the desk!"
Wait,... what? Network cables are supposed to go "click" when plugged into something, yes? Why, then, does this 'ere green one just slide in and, perhaps more importantly, out of its 'ole? Might the periodic "network errors" afflicting the PC up there be due to a quid's worth of string not staying put?
Fortunately MrCreosote (the new NAS) came with a network cable which clicked satisfyingly into place at both ends. Even if it is the wrong colour.