[Hikikomori]

Think I was able to reproduce it. I configured my router to drop established connections for IP 169.150.221.147 in my policy attached to my wan interface for outgoing traffic (important detail, inbound would drop the syn/ack instead). For reference its an Ubiquiti Edgerouter that uses iptables to filter traffic.

In the linked picture [0] I have packet #436 selected, its a retransmission of the handshake syn/ack with seq=0 ack=1, repeating a few times later, same as OP.

So as others suggested, likely a misconfigured BOGON rule with 169.0.0.0/8, but also matching outbound established connections rather than new/any state for some reason.

[0] https://i.imgur.com/AwJGI3W.png

[js2]

Good find, that fits the symptoms perfectly and is more likely than not a problem with the firewall on the source end (the campus network). Did you email the author?

[Hikikomori]

As a network engineer it piqued my interest (unemployment is booring) as there were no completely satisfying answers, though some were close. Thought it was the old MTU problem at first but as it was the ack of the handshake being retransmitted it wasn't likely. So tried a few things with my router.

This is how you get NOCs to help you quickly, give them not only the problem but the root cause as well. Its not that they (or me) are lazy, its just that it can be so many things that can be a potential cause of problems, especially when you only have incomplete information to go on.