Pepwave Surf SOHO MK3 - receiving pop-ups on multiple devices

This is my first post to the forum.

Installed Pepwave Surf SOHO MK3 on May 22, 2017 for a home network. Up to 10 devices connect via WiFi. Setup DNS settings to OpenDNS family setting. Router works well. Received recommendation from Tom’s Hardware as I was looking for a more robust, secure router than the standard home brand.

Having an issue that is affecting all devices. Primary used devices connected wirelessly are laptop and desktop both running Win10 os. We are consistently getting browser Youtube seach pop-ups on a daily basis and or other video popups. Recently blocked Youtube entirely, but still receiving video pop-ups from other sites. We cannot detect Malware after multiple scans that may be causing the issue. Used Malwarebytes, FRST among others.

I admit that I am a novice but since the issue is occurring on multiple devices I was wondering if there is a way to track down where the attack is coming from by looking at router log. Is it possible that a website could be attacking my network. vs a Malware issue? Some of the attacks are porn related. On the device/computer side I can see browser history of searches occurring but we are not making them. They start as bing or google image searches. Sometimes the searches turn off the safe settings by itself.

Is this something you can help with? My goal is to find the root cause, block it and be able to enjoy our network.

thank you.