Site intermittently unavailable - pcaps included

A couple weeks ago, we had an issue where a website on the Internet that users had been using for quite a while suddenly was inaccessible.

After a bit of troubleshooting, checking firewall logs and looking at the pcap, I couldn't see anything that might be causing the issue so I pushed the traffic over to our secondary datacenter(different firewall and Internet) as a workaround. Site worked fine for users for a couple weeks after that. Thinking I would get back to it later, I never touched it the last couple weeks. Well, yesterday the same issue came up, so I removed the change I made and started pushing the traffic back over the primary DC firewall/Internet. After that change, the site was again accessible.

I have pcaps but I don't see anything that might be causing the issue.

Any ideas?

First pcap(site not working)

https://drive.google.com/file/d/1RGNjueEdBSrteHW3_2HXsFpOphqXDJ5j/view?usp=sharing

Second pcap(site working)

https://drive.google.com/file/d/1P9wFjHN6K_uuWJb63fByO1hsAiucwryw/view?usp=sharing