HELP Getting 1200 MBPS speeds on my plan

Somewhat of a piggyback post, but I have the same issues/problem that I can't seem to resolve. The guy who started this other thread seemed to have solved his problem of not getting the 1200mbps speeds of the plan/package he was paying for. I'm in the same boat. And ironically I have an almost identical hardware setup to the OP in that post. I would have replied in that thread, but it's closed. I wish I could pick his brain about what he did to fix it. He left it as sort of a mystery with the last post being, "let’s say I discovered something about bonding, it doubled my upload speed" but gave us no details lol. I'm more concerned about simply just getting the speeds that I'm paying for on my Comcast 1200mbps plan (which I'm not). Here's the original Xfinity post I'm talking about: Internet 1200 Mbps plan

 

Like I said, that guy had the same stuff as me: ARRIS S33 cable modem and an ASUS ROG GT-AX11000 router using the 2.5gbe port from the modem to the 2.5gbe port on the router and then from the router to the 2.5gbe ethernet port on my ASUS Crosshair Hero VIII motherboard (Realtek 2.5 ethernet LAN onboard). All using Cat7 or better cables. No matter what I did in the past, I could never get over 1000mbps download speeds on my desktop PC this way. The only way I could see 1200mbps+ speeds was a direct modem-to-PC connection. Sadly, I can't even get that to work now days. I spent an hour on the phone today with Xfinity tech support that was a total waste of time. A lot of worthless advice i.e. "unplug the ethernet cable and plug it back in" and "unplug the power on the modem and let it reset and plug it all back in" etc. Like I haven't tried that already?

 

I've also done insane amounts of troubleshooting the onboard NIC card/controller, made sure all drivers and firmware were up to date on everything, made sure to flush DNS, reset the network adapters, run all kinds of tests that check out just fine, you name it. Over a year ago, I asked this same question on the ASUS forums and didn't get any answers either. Here's that thread for reference: HELP PROPER CONFIG GT-AX11000 2.5GE + 2.5GE SWITCH + 2.5G MODEM FOR OVER 1GBPS...

 

They did make a technician appointment for me for tomorrow. But after that was set, I got a call from "advanced support" or something and we did all those worthless troubleshooting ideas I described previously. After that, I got an automated call to let me know my network issues have been resolved or something, which is totally untrue. So I hope the field tech guy is still coming tomorrow. I'm hoping it's a problem on the ISP side, but considering I've never once been able to make this work previously doesn't give me much hope.

 

So, does anyone have any suggestions on how to get the 1200mbps speed with the hardware configuration I laid out? Like I showed, at least 1 other person seems to have figured it out!

Thanks in advance!