Connection blocking to specific IP address

Within the last week, it appears connecting to a specific IP address (91.189.95.85) has become throttled / blocked / rate limited. I can only make somewhere in the neighborhood of 7 open connections before I am temporarily blocked from making any more simultaneous connections.

This is not a problem on my home LAN internal network as I have tested this at multiple cox home networks in the same neighborhood with the same results. I have also run the same tests from non-cox networks (including from an AWS machine), and my test is not being blocked there in any capacity.

This leads me to believe there is something new on the cox network that is rate-limiting or throttling outbound connections going to a single destination.

The test I am running is:

xargs -I % -P 5 curl -I "http://ppa.launchpad.net/ondrej/php/ubuntu/pool/main/p/php-imagick/php8.0-imagick_3.4.4+php8.0+3.4.4-7+ubuntu20.04.1+deb.sury.org+1_amd64.deb" < <(printf '%s\n' {1..8})

using {1..7} will complete, whereas {1..8} will hang on the last connection, and eventually time out with: 

curl: (7) Failed to connect to ppa.launchpad.net port 80: Operation timed out

I am unsure where else to go to find a resolution to this problem.