what wired speeds do you get? Always test wired first as we can troubleshoot wifi all days but if the bottleneck is the wired connection or the provisioning, its a waste. 

What Xfinity router did you have? 

I have the XB8.  I’m getting 1300 wire speed.  Xfinity technician was here and says it has to be the router.  I plugged the XB8 back in and my wifi speeds are back to 1100-1200.

1. You're not getting 1300mpbs wired speeds on the G34. It doesn’t have multigig ports. only gigabit. that makes me doubt all your measurements. And xfinity only certifies it to 934mbps. https://assets.xfinity.com/assets/dotcom/projects/cix-4997_compatible-devices/2024.09.18%20Full%20List%20of%20Compatible%20Devices.pdf
2. you can’t compare the XB8 which is a triband 6E with 160hz wide channels to the G34. The equivalent performance would be more the G54. 
3. Not 100% because I couldn’t find the official specs but I my understanding of the G34 is its wifi is only 80hz wide on 5ghz with a 4x4 antenna. and most devices are only 2x2 antenna (phones/tablets/computers). so your absolute maximum link speed (not throughput) is a link of 1200mbps. Thats the link speed. throughput tends to be 55-65% of that. And thats at close range without inteference/obstructions. 
4. You can probably get some faster speeds (more like 500-600mbps) but you won’t hit multigig with the g34. You can try optimizing your 5ghz wifi channel https://arris.my.salesforce-sites.com/consumers/articles/General_FAQs/G34-G36-Changing-the-Wi-Fi-Channel

Again, you’re not comparing equivelent routers. Or even if you’re on the same channel. The XB8 supports 6ghz which has much less intererence and supports 160hz wide (320hz wide in wifi 7) channels. 

So, it sounds like I should return the G34 and pay the $15/mo for the XB8.

Thank you!

I wouldn't say that. Most devices don't use more than 50-80mbps because that's all it takes to steam a 4k steam. Gaming doesn't take any more than that either. It's only if you're moving massive files that you'll see a benefit. You can always pay the $15 a month (180 a year) just to say "my Wi-Fi is fast" but you won't see any difference day to day (for the majority of people). 

Understood and I agree.  Thanks again!!