So, it sounds like one of the following is true:
1. The needed QoS settings for such on the routers don't exist. (Google Home offers such a service, although I'm not sure what hardware you need: <
https://support.google.com/wifi/answer/6246483?hl=en>.)
2. Local leadership doesn't have access to the administrative settings of the routers.
If #2 is true, you'd probably need to turn the Wi-Fi off while keeping the ethernet on (if you can even change that), plug another router into it (with such as a CAT6 or CAT5e cable) which other router is configured appropriately for your needs, and use the Wi-Fi from the other router. If you can't turn the Wi-Fi off, then if it has an annenta, you can unscrew it to disable the Wi-Fi. If there's no external antenna, maybe you could put the router inside something designed to inhibit the radio waves of the Wi-Fi, if that's legal. I don't know.
If the specific QoS settings just don't exist, but you do have access to other settings, you might consider enabling MAC addressing (adding the needed MAC addresses to the list first). That way, only the computers you add can use the Wi-Fi. Just be sure to disable MAC addressing after this situation is no longer needed, or no one else will be able to use the Wi-Fi. Don't block yourself out, though; you may want to do this via a computer connected via an ethernet cable (CAT6 or CAT5e).
On most routers, you can go to the router settings by typing in something like
192.168.0.1
in your location bar (on a web browser connected to the router via Ethernet or Wi-Fi).
And then type in the username and password (if you have it) on the page that loads. This isn't the same as the Wi-Fi login. The default login tends to be on the router (but they've probably been changed).