how to reduce ping / latency with 5g home internet

I'm currently getting 300-400+ms pings with my black rectangle TMobile router.  The speeds are super variable as well, ranging from 3-30 down and 3-30 up.  I get better connectivity using my cellphone on TMobile than the router does.  I've talked with TMO support a couple of times, and they updated the address on the device (it was set to my old address for some reason).  It helped with up/download speeds I'm not getting what I should and the ping response time hasn't changed.  We have quite a few devices on the network - cell phones, laptops, smart home devices but I've never had a problem with the same kind of usage with other ISPs.  I can't simply use software to correct the issue since it applies to several devices, and my work machine which I'm not an admin.  I also have problems using my VPN with this service - I've talked with TechSupport at work and they installed Global Protect instead of using the built in Win11 VPN, but its super flaky at best given the inconsistencies with the network. Any thoughts / ideas would be a great help!