Cordless phone interference with D6300 Netgear Modem Router

I have a vtech 17550 cordless phone that operates at 1.88-1.9GHz. This phone actually claims to be WI-FI friendly as it states on the box. I just bought this phone from Harvey Norman so it's a fairly newish model.

I also have a Netgear D6300 modem router which is a dual band modem that operates at 2.4GHz as well as 5GHz. I must operate at these two frequencies as my laptop can't detect the 5GHz WI-FI connection.

My problem is that I am getting really bad inteference on my cordless phone in the form of constant static noise.

What I have tried:
- Moving the cordless phone base to another room (about 8 metres away from the modem separated by 2 walls) – didn't help.
- Plugging in our corded phone in the phone socket used by my cordless phone to eliminate potential issues with the phone line or phone itself – no issues here.
- Disabling the 2.4GHz signal on my modem router so only the 5GHz was accessable – didn't help.
- Tried using a different ADSL filter to eliminate problems with the filter – didn't help.
- Tried using a new phone line cable to eliminate problems with the cable – didn't help.
- Tried switching channels on my modem router to reduce interference – didn't help.

I don't know what else to do. If I switch off my modem, there is no interference but I need my modem.

I suspect that my issue lies with either the filter/splitter or the D6300 modem/router.

Can anyone help solve this annoying problem once and for all?