Can't browse the subdomain after visiting a couple of pages of the website made with laravel

I developed this website using Laravel 5.5 for my research group and uploaded it to my university web host. The website's address is in the format of xxxx.cse.yyyy.edu .

When I browse some pages of this website it gets inaccessible and I can't even access the cse.yyyy.edu subdomain anymore for a while (usually after 10-12 hours). I can ping the IP address of the CSE subdomain but can't ping the domain address (possibly a DNS issue?). Although I am not sure, I think restarting my local router makes the website accessible again.

The only thing out of the ordinary about the website is the insecure login page that is not using https at the moment. Other than that, everything is just straightforward laravel code adopted from the original laravel documentations.

I'd be happy to provide more information but I don't really know what kind of info I should be providing here.

What do you think might be causing this problem? Thank you in advance!