I have FIOS Quantum Gateway 100 mbs. I started having issues with certain webpages being blocked by McAfee Home Network Protection by Verizon. The warning page that appeared stated "Whoa, we flagged this site as malicious. Sure you want to go there? This site could steal your sensitive info and hijack your device with malware.". It would give you the option to continue to the site anyway, but it wouldn't actually do it. At the same time I had certain web pages that had some information stripped from it. All of the websites I had either problem with worked fine about a week ago. This was happening on all of my devices. Using my phone, I turned off it's WIFI access and used my DATA. It went to all of the sites in question and they were fine. I then used another company's internet service and all was well with that too.
I looked at the router settings, but they looked OK. I then searched my account to see if anything changed and it had. I noticed that Home Network Protection was listed as my current account setting. I never saw this feature before, nor did I ask for it. So I tried to disable it, but couldn't. I started a chat with Verizon Technical Support to have them disable it. They had no idea what I was talking about and even asked me where I saw this feature in my account. I told the where and got the response that I just needed to uninstall it from my computer. I told them I had not loaded anything to my computer and this issue was on ALL of my devices. I could tell they were operating by a "script" and asked them to actually READ what I stated. I got absolutely nowhere.
So, just for grins and giggles, I decidied to restore my modem from a restore point made a month ago. That did the trick. I'm not sure which setting on my modem caused the issue. I starting to think it was either a hidden setting or a virus, but I think a virus would be a stretch. To be safe, I imediately saved the modems configuration file to my computer. Verizon's technical support doesn't seem to have knowledge about it. If someone else has this issue I hope this helps.