I suspect that you are connecting on the 2.4 GHz band rather than the faster 5GHz band - because these are now combined into 1 SSID.
I have my own router with them separated and for example, my Macbook Air and iPhones 7/10/11 both get 220mbps on my 200Mbps wifi package (and 220 on ethernet of course). However, on wifi, they only get that when I put them onto the 5GHz network. Sat in the same spot if I then flick them over to the 2.4GHz network, they max out at 50-60mbps (others on here get even lower [<50] on their set ups) - it's just the limitations of the technology!
So you could try separating the SSID's by doing this...
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Type in
http://192.168.0.1 into your web browser’s url box and login with settings password on the Hub's base sticker (or your own if you changed it). Then in Advanced>wireless signal >smart wifi - tick the disable “channel optimisation” box or “Smart Wifi” box and save settings. May be different pathways and wording on the 3 Hub types
Then, go to advanced>wireless signal>security, rename the 2.4 & 5 GHz network ssid's. Just type over to change 'em to whatever you like and something that will differentiate them (e.g - PaulFC_2 & PaulFC_5) Try to avoid spaces and periods in the SSID names as they can cause issues with certain devices. Use the same password for simplicity, Then, apply settings and restart the Hub. Your 2 wifi networks will now be clearly separated - and you can then select the network you want each device to connect to… individually from the "available networks" list on each of your devices.
Note all your wifi devices will need re-connecting to the new SSID's and passwords.
All things being equal, 5 GHz is always better/faster and subject to less congestion/interference (and is better for iDevice speeds than the 2.4 one - although the 2.4 one has the better "range" and will be needed when the 5 GHz drops out of range and some older/cheaper/dumber devices can only use this one.
You should also use a wifi analyser App (or Airport Utility on iOS) to check which 2.4 channels are being heavily used around you and move yours to one of numbers 1,6,11 that is least so, but it wont help if there is other interference.
See if these changes help - you will lose any “seamless roaming” benefits but it may not matter and you can always change the settings back by doing a " pinhole factory reset " if you prefer the way it was - or it doesn’t help.
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John
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I do not work for VM. My services: HD TV on VIP (+ Sky Sports & Movies & BT sport), x3 V6 boxes (1 wired, 2 on WiFi) Hub5 in modem mode with Apple Airport Extreme Router +2 Airport Express's & TP-Link Archer C64 WAP. On Volt 350Mbps, Talk Anytime Phone, x2 Mobile SIM only iPhones.