Rak7240 not connecting to mobile WiFi hotspot

I have a Rak7240 Gateway and have been using it on my house WiFi and sometimes with my phone in hotspot mode with no problems for a few months. Today I tried to connect it to a mobile hotspot device (Netgear AirCard 815S), but it won’t connect. Switching back to the other hotspots makes it work again. The gateway is not on the blocked devices list for the mobile hotspot, and I have been able to connect several devices to the mobile hotspot without any problem. I’ve tried several times and double-checked the password and Encryption each time. SSID and password are all lowercase letters. The Encryption is WPA2-PSK, and I tried setting the hotspot up with no encryption, and the gateway still didn’t connect. Is there anything else I can do to troubleshoot this problem?