Airport Extreme (old style) connecting to Plusnet router?

We are confused by the information in your post.

In the title, you state that the AirPort Extreme (old style) is connecting to a Plusnet router.

In your post, you ask if the Plusnet router can connect to the AirPort Extreme.

Which device is your "main" router at the present time? What will connect to what?

When you say that you have an "old style" AirPort Extreme, would that be the old "round" or "dome" shaped AirPort Extreme.....or.....would that be the old "square" shaped AirPort Extreme? The model number......it is on the bottom of the AirPort Extreme......starts with an "A" followed by four numbers.......would be very useful.

You don't tell us what operating system that your Mac or PC is using. Can you provide that information?

If you have a Mac and do not know what operating system it is running, click the Apple icon in the upper left corner of the screen, then click About This Mac. Post back with the OS X Version number that you see there.

I am upgrading to Fibre Optic (from Plusnet). They have provided a new router & BT engineer will bring a BT Openreach Modem.

Then the Plusnet router will be your "main" router.

The AirPort Extreme can connect to the Plusnet router, but it must be with a permanent, wired Ethernet cable connection. Once the AirPort Extreme is set up, the AirPort Express can connect using wireless or Ethernet to the AirPort Extreme.

Where will the AirPort Extreme be located in relation to the Plusnet router? Close by? A few rooms away?

If both the Plusnet and AirPort Extreme will be producing a wireless signal, then you need to make sure that they are separated by about 5-6 feet, or a few meters, in order to minimize the chances of interference occurring between them.

If you don't plan to use the wireless signal from the Plusnet router, a better solution would be to turn off the wireless function. That would solve the potential wireless interference issue and allow the AirPort Extreme to be located close to the Plusnet router if that type of location is needed.

Plus net is no doubt charging you a monthly fee for rental equipment.

If you have the Airport Extreme and Express, why complicate things, incur interference and pay extra with a router you don't need?

My provider charges $9.00 a month for rent of a router. That is $96 per year, plus taxes. My AE paid for itself 2 years ago. (I also have the 5th generation)

My Airport Extreme and express do an excellent job of providing wifi within my 4,000 sq/ft house and well into my 3.5 acres as well.

ire= annoyance?

not.....

just a suggestion to avoid redundancy. I have no use for any other router other than my Extreme.

PS. Check your bill for rental fees, hope you are right. Kinda makes my cable company look bad.