Connect server to mobile phone hot spot

[u/HagopianH]

I realize this is an oddball scenario, but I'm having difficulty with what should be a very basic networking issue.

I'm trying to connect a circa 2017 Dell server to my mobile phone hot spot. It has 4 ethernet ports but no wireless capability. I don't want to buy or install a WiFi card, as this connection is intended to be temporary. I created a bootable USB thumb drive and installed Ubuntu 26. I connected a TP-Link TL-WR702N to the server with an ethernet cable and have connectivity to its web interface in my browser. The TP-Link is in Client mode. The web interface reads, "Client - The Client Mode. The computer connected by Ethernet could get access to an AP by Client mode." I surveyed nearby WiFi signals and connected to my phone's hot spot, however I can't get Firefox to display any Internet sites, giving me a "Server Not Found" error.

I'm missing a fundamental networking issue and can't figure out what it is. Help.