Dell Inspiron 15 constantly disconnecting and reconnecting to wifi since new modem installed

Hello,

I recently got a new modem: Centurylink model C4000XG to upgrade my internet speed. All other devices in the home work perfectly fine, but my 2017 Dell Inspiron 15 will connect, say secured, stay connected for a couple seconds, disconnect, sometimes it will say connected without internet, but it's cycling through this process constantly.

I've scoured these forums and have tried every single thing suggested for wifi connection issues including:

• Changing wifi channels, tried 11, 10, 9, 6, 3
• Changing the channel on the modem to match
• Changing 802.11b/g 2.4GHz to 20MHz only
• Changing the modem to match
• Changed 5.2 to 20MHz
• Making sure power settings are ideal
• Checking for driver updates, but I can only check on my computer for something already downloaded because I can't stay connected to the internet long enough to download anything.
• Tried forgetting, disabling and re-enabling, reconnecting
• Restarting computer
• Turned roaming aggressiveness up to highest
• Turned on WWM
• Disabling bluetooth
• Making sure Preferred Band is 2.4GHz
• McAfee and SmartByte are not installed
• I turned off firewalls for Defender
• Made sure all SSID channels are broadcasting and matching radio configs
• Couple other things I can't even remember

Driver: Intel(R) Dual Band Wireless-AC 3160 version 18.11.0.8 6/22/2015

If I need an updated driver, how can I get it without access to the internet?

Does anybody out there have any other ideas? I'm desperate!

Thanks,

Felicity