As I expected the TOT thunder is approximately 3 times faster in the tablet compared to the router.
From what I understand, TOT have 60 MHz of spectrum on band 40 so devices that support 3CA (carrier aggregation) can have 3×20MHz simultaneous connections to increase the speed.
I also have the same TOT thunder SIM card but it's a shame that decent routers above CAT 4 are so expensive.