Ok, its taken me 3 days but I think I have finally figured this out, and I'm so chuffed that i need to share.....

I have just bought a PS4 to replace an ageing PS3 I have started playing on again with the kids, along with a new telly in the Man cave. The problem was that as soon as I tuned the thing on it killed the internet connection dead.

The router was OK before the PS4 was connected, and with the PS3 on, but I was getting download speeds of 19kbps at worst, and nothing else was connecting in the house via either ethernet or wifi when the PS4 was on.

So I had to do a bit of rummaging around. I changed the router to the BT hub (pants) and god a decent connection and it was reasonably stable, at which point i thought it was my router, which was unlikely as its a Billion Bipac 7800DXL.

So I pulled up the SNR settings on the routers and noted that when the PS4 was switched on the SNR dropped on both routers by about 3-4db. Which was fine on the BT hub as it was running an exchange setting at about 6, but my router is tweaked to run 4 so i get a decent speed, which had been ok in the past, but as the PS4 was dropping the SNR by that amount the signal was dropping!

I set the internet connection to off in the PS4 then happened to notice that it was affecting the SNR on my router even though it wasn't connected! I tried it in an extension and moved the router farther away, same result....

i then happened to put it on the floor for some reason, and the problem went away, TOTALLY!

I surmise that this is because the racking in that corner of the room is metal, and is amplifying some sort of interference from the PS4. Normal service is now resumed on the inter webs and the moral of the story is DO NOT put your PS4 on a metal shelf within 3m of your router!!  There is nothing that can't be fixed with a hammer😜😜
FFRR 4.4 SDV8 Autobiography Santorini Black.
Fiat 500x 1.4 multiair Lounge 2015
2010 LR D4 Commercial 2.7 TDV6

Haha intiguing. Thanks for the tip.

 Formerly happymadison1978

Is the PS4 hardwired via CAT5 to the router or using WiFi? FFRR MY06 facelift With TDV8 Alloys Zeros/ATR's
Mantec Sump Guard, Rigid Load liner, MY10 BT upgrade.

tried it with both, it worked slightly better with ethernet cable, but even when it wasn't connected either way it affected the SNR. There is nothing that can't be fixed with a hammer😜😜
FFRR 4.4 SDV8 Autobiography Santorini Black.
Fiat 500x 1.4 multiair Lounge 2015
2010 LR D4 Commercial 2.7 TDV6

I would try it with wifi off and no lan cable and see if with it just playing in offline mode it does it and effects the rest of the network.

I have a feeling your cabinet is as you've suggested attenuating from hdd or fan vibrations and affecting the ads.

If the above is true then it's time to put rubber feet on the cab and just under the ps4... FFRR MY06 facelift With TDV8 Alloys Zeros/ATR's
Mantec Sump Guard, Rigid Load liner, MY10 BT upgrade.

Got a new cabinet

all hunky dory now

The original was just some metal shelving, so not ideal. It did affect it in Offline mode before, itterally could lift it from the floor to the shelf and watch the SNR on the router drop through the floor, was reading -1.9 at one point which is not good..... then but it back on the shelf and watch it climb back to 5. There is nothing that can't be fixed with a hammer😜😜
FFRR 4.4 SDV8 Autobiography Santorini Black.
Fiat 500x 1.4 multiair Lounge 2015
2010 LR D4 Commercial 2.7 TDV6