Would a Netgear Nighthawk work with a Calix ONT?

Here is my problem:

I got fiber in my area and It's IPoE with a Calix ONT Giga Point 803G. When I hook up 3 routers directly to the ONT it works for 30 mins then drops speeds down to 500 down and 20 to 70 up. On NTOPNG it says I'm being attacked from my ISP and says they're flow flooding. I got all kinds of IPs that are bad according to NTOPNG from China, Russian, UK to Washington US. I don't believe an ounce that my ISP is attacking me so it's something to do with Calix ONT.

I've been talking to my isp and they say that it's not restricted in any way on their end. I even showed them this article that explains what happens here: https://calix.force.com/CalixCommunity/s/article/Preventing-subscribers-from-using-third-party-routers-gateways they shot that down immediately and said that is not on their system and they don't do walled gardens which this ISP has been awesome so I'm glad they don't.

If the ISP doesn't know that they have this walled garden can the nighthawk work around this walled garden approach?

Also, my ISP is saying the Calix ONT is dumb and only does one thing transfer light to ethernet. Which is hard to believe.

We asked at the beginning of the install of the fiber can we bridge the Calix Router because I had to do this with ATT Router. They said that was not recommended and to hook it up to the ONT. The other day the guy from our ISP that has tried to rack his brain in helping us said to hook it up ONT > Calix Router > Your router and see if it works.

I did get it to work after DMZing it but had to turn on the DHCP server on Calix Router which in turn I have a double NAT now on different subnets. With using the Calix Router as a conduit NTOPNG is fine and all green at the top left so no more bad IPs immediately after this configuration. This approach is giving me latency and some things not working right.

I'm wanting to replace the GigaSpire Router with the Nighthawk RAX45 AX4300.

We where thinking that since the GigaSpire can't be bridged according to our ISP. Could the NETGEAR - Nighthawk RAX45 AX4300

be bridged to go to our pfsense? We have read & heard from our ISP, people on their network are using Nighthawks but could this configuration work with this nighthawk?

Calix ONT > Nighthawk RAX45 AX4300 > pfsense

Thanks for any help!