Cannot connect to wifi

[#1]

Connection has been dropping on and off for a while now, usually only for a couple of minutes. Today it has dropped off completely. The hub is lit up blue and hub manager says it is connected but no devices can connect to it.
This was a minor annoyance but is now a serious issue as I am working from home and am constantly hindered. Really need help resolving this issue.

[#2]

Ensure you give both router bands (2.4/5ghz) different SSID names; this may help.
Try turning off temporarily the router security; do you then get connection?
If so, turn security on, and start again.
Ensure router is not near a device causing possible interference eg Wireless door bell/ Wireless
Central Heating gadget etc
D/Load a wifi analyser programme to identify which channels in your locale are most used;
then set Router channels to the least used/not used.

[#3]

Hi, thank you for your suggestions but unfortunately they didn't work- still unable to connect any devices to the WiFi.