I've got Comcast and I've never seen throttling. I get over provisioned speeds. I pay for 300, I get 320.
The only time I got less was when I upgraded the FW on my 1900P and it was wonky. Downgraded and speeds were back to normal.
Your configuration seems fine. Did you modify dnsmasq.conf to something custom that could possibly break?
Other than that, you might be experiencing something on Google's side...
You can copy the dnsmasq.conf file over to /jffs/configs and make the edits yourself. Any conf file in there will override their corresponding stock file.
Most likely some corruption on the router. For the longest time I couldn't access a tech website that I frequent that I know is always up. Using another device to try to access that website also resulted in an unreachable error. Only way to fix, at least for me, was to reset the router and...
You know what, try a different DNS server, like Google's or your ISP. I tried Cloudflare and found that their implementation was incomplete or lacking. Kept giving me DNSSEC errors.
Probably waiting for the WAN interface to come up. I have a script to change the initcwnd and initrwnd in wan-start, but won't run properly. Even though it is in the wan-start script file, I have to place a two minute sleep timer before executing my script.
^^^ You have to give it the -update argument.
Small bug report though:
After updating, very last question is to see if I want the script to restart qos or no, I hit 2 (no) and it gives me a "bad number" with "[:" IIRC.