Night Hawk XR 500 getting [DoS Attack: IP Spoofing] from source: 192.168.1.22

Hi there - that's unlikely to be related (https://community.netgear.com/t5/Nighthawk-Pro-Gaming-Routers/DoS-Attack-IP-Spoofing-from-source-192-168-1-1-port-57985-Monday/m-p/1716507#M8772)

It's more likely that either your Internet speeds have dropped from your provider, or there's a setting on the router.

To figure out if it's the first one, try connecting directly to your modem and running a speedtest. What are your speeds? Then connect the same device back to your XR500, are the speeds the same or lower?

If they're lower, please follow this guide to make sure none of your settings are slowing down the router: http://support.netduma.com/en/support/solutions/articles/16000076586-dumaos-optimal-settings-guide-maxmimum-bandwidth-speeds