If the above doesn't do it you could always try this to force the blink onto the 2.4 band...
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Go into the Hub’s settings. 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 the“Smart Wifi” box and save settings. May be different pathways and wording on the 3 Hub types This (message 2) is for a Hub3… https://community.virginmedia.com/t5/Networking-and-WiFi/Hub-3-Wi-Fi-constantly-dropping/td-p/5391375
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 - Chantelle_2 & Chantelle_5). Try to avoid spaces and periods in the SSID names as they can cause issues with certain devices. Use the same password for both for simplicity,
Then, apply settings and restart the Hub. Your 2 wifi networks will now be clearly separated onto the two different SSID's - 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 or “specialised” devices can only use this one - like the Blink.
You should also use a wifi analyser App (or Airport Utility on iOS) to check which of the 2.4 channels are being heavily used around you and change yours to one of numbers 1,6,11 that is least in use by others.
See if these changes help - you will lose any “seamless roaming” benefits but it shouldn't matter and you can always change the settings back to what they wereby doing a " pinhole factory reset " if you prefer the way it was - or it doesn’t help.