High Ping when using ps4

I am currently using a SMARTY 5G sim in a ZTE mc801a router, connected via Ethernet cable to the PS4.

My download speed varies, have seen it at 16 mbps to 90 mbps. Upload has always been low at max 2 mbps.

But my ping when play Apex Legends/Fifa is fluctuating around 60-120.

I have tried to apply custom DNS on the PS4 with the Google/Cloudflare DNS, but do not see any difference compared to auto settings.

Is there anyway I can reduce the ping?, as it’s causing slight lag/delays in gameplay.

Or do I need to get a better router for lower ping?

Please advise.