Is there no Model Number on the Router? not to worry, I going to assume the Router is the EE Locked Down version of the Zyxel if it has 4 External Antenna Ports, as a few of Zyxel Router 5G have.
The second link you have posted for the Antenna ( QuPanel-5G-LTE-MIMO-4x4 ) does look as though it covers the UK 5G Frequencies (N78) and looking at the Data Spec there does seem to be some confusion as to whether it covers EE's new 5G 700mhz Band (N28) but it does state it covers this Band on 4G (LTE), so assuming each of the 4 Antennas and Feeders within the Unit are the same spec then it should cover the 5G Band N28.
Also, it looks like the Coax Feeder Plugs on the above Aerial are SMA Type, so if they are, your probably going to need 4 x Adaptors to suit the Router Antenna Sockets, Im not sure what they are on the Router but if I was to hazard a guess probably TS9 Type, probably best to wait and see when the Antenna is delivered to double check, if you decide to go down this route.
Other than that I have not come across the above make of 5G 4x4 Mimo Aerial before, other than they are based in Poland, so Im not in a position to comment on the Aerials build quality and its working performance or compare it to my recommendations in my first Post, so if you do decide on this one perhaps let us know your thoughts of it.
