Smartphone Doesn't Show Wi-fi Connection.

I have a Vodafone Mobile Modem that I always connect to my PC via USB cable. Up to 10 devices can connect via Wi-Fi. Since the past weekend I can't connect my LG Leon smartphone. It doesn't even show the network although it's under Saved Wi-Fi. Also, the phone shows 3-4 other Wi-Fi networks. There's nothing between the phone and the modem.

I have done the following:

• Disconnected the modem from the PC and turned it off.
• Turned on the modem.
• Restarted the phone.
• Plugged in a Wi-Fi adapter (USB port on the PC) and connected within 5 seconds.
• Enabled Wi-Fi on an old mediocre Samsung Galaxy Pocket Neo and connected within 5 seconds.
• Checked the Settings on the phone and everything is still the same.

Any idea why my phone is suddenly not showing the Wi-Fi network it has connected to for more the past 2 years?

 

I can't change the channel.

Less than an hour after posting this thread, the phone detected the home network and automatically connected!
And this morning it again automatically connected.

 

Confucius says: "They who have computer... will have problems."

 

And today the LG phone doesn't show my Wi-Fi network.
I checked the modem's Wi-Fi settings on the internet and changed Channel from Automatic to 7. And I'm connected.
Let's see how long this lasts...

PS This still doesn't explain why...

• Everything worked fine for 2+ years.
• The 4+ year old Samsung connected within minutes prior to, and after changing the channel.
• The PC, via a Wi-Fi adapter, connected within minutes prior to, and after changing the channel.

And now I'm off for a poo to reminisce...

PPS TimW gave me permission...

 

Quick follow up...

I'm still connected.