Ok, so last month I switched from Slingshot to Contact fiber because of the $300 credit Contact were offering for their power/fiber bundle. With Slingshot I had one of their locked routers but with Contact I'm using my Fritzbox 7490 that I used a couple of years ago when I was with them with no problems at all.

Everything was fine with Slingshot, and maybe this is a coincidence I don't know (hence the title), but within days of joining Contact my internet stability started getting progressively worse. Speeds are fine, but I keep losing connection to the ISP. The event log on the router will usually say that the internet connection has been cleared followed by the message "Internet connection has failed. Reason for error: 2 (dhcpv4 no answer on discover)", which I understand means that the router can't talk to the ISP, and the optical light on the ONT box won't be lit up, it usually comes back on after a minute or so. I get a similar error when IPv6 is enabled. 

This started off happening a couple of times a day, now it's happening every 10-20 minutes or less. 

I contacted Contact and they told me it was my router, and I'm not that computer savvy but I figured if I removed the ethernet cable between the ONT and the router and the Optical light on the ONT was still turning off every 10 minutes or so then I could rule out the router, and sure enough, within 7 minutes of unplugging the ethernet cable the optical light went off and the power light started flashing, then the power light went solid green and a minute later so did the optical light. Watched it a bit longer to see if it happened again, and 10 minutes later exact same thing.

The thing is as I said I'm not that computer savvy, so I'm not sure if that's normal behavior when you've removed the ethernet cable from the ONT box or not, hence my question.

Do you think this is a problem with my ONT (Model 100), ISP, or could it be the router?