Fibre Optic Broadband HELL... (or iPhone HELL)... (Or both?)

[Sterillium]

I recently got a new fibre optic deal to replace my ageing old broadband...

All was well, as I moved from a steady trickle of 9 - 12 mbps onto my new (guaranteed) 38 - 40 mbps.

The only problem is, since I've had the new router and what is now a fairly constant (although still not what I was guaranteed!) flow of 25 - 35 mbps, my wireless at home has become really unreliable on my iPhone.

Whenever I try to use the wifi, inevitably, any page I look at will begin hanging, stuck, with a little endless wheel of "loading" on the top bar. This happens on all sites, intermittently.

So far, I have reported it to the provider and been told:

It's a problem at my junction box. (Engineer "fixed" this... no change).
It's a problem on the wire outside my house. (Engineer "fixed" this... no change).
It's the router. (We had a new one sent out"... no change).
It's a problem in the wires INSIDE your house. (Engineer supposedly coming soon).

And so far, on my iPhone (the worst offender for hanging) I have done:

An update. (No change).
A full reset. (No change).
Tried a new DNS. (No change).
Factory reset. (No change).

I'm at a loss as to what to try next.

The broadband seems to be FAST and often when I test it, it's right there pumping out a decent (if not the guaranteed) amount... but it just seems to drop on and off all the time. Clearly, I'm NOT getting what I am paying for and am about to start the process of unhooking from the provider as they clearly are not providing.

It never did this back on normal broadband.

Any ideas?

[Sterillium]

It's a PlusNet HUB thing...

Having looked on the HUB manager I can see that it sends out both 2.4 and 5 at the same time with the same wireless name etc.

The devices seem to be split across the two (some on 2.4 and some on 5) but there are two iPhones, one iPad, one XBOX One and one laptop. It seems to be mainly the phones and iPad that struggle.

I'm not sure what I should do (I am clueless with this stuff).

[Sterillium]

I have no idea what I am doing, but...

I've managed to find "Advanced Settings" and a little map that shows my home devices (XBOX, Laptop, 2 phones and an iPAD) all on a map of where they are.

My iPhone is linked to 5 - everything else is linked to 2.4.

I can't see how to "assign" them to one or the other, and I don't know which is best anyway, but I have now deactivated the stream of 5 and my iPhone has popped up - along with ALL devices - in the 2.4 list.

Am I doing ANYTHING worthwhile here?

[Sterillium]

Thanks for all the help so far chaps.

[Sterillium]

I've shut the 5ghz off... is this as good as separating them?