Test your real ping from the modem and from a wired connection directly (no wifi).

That will give you a good reference of what to expect in term of latency and bandwidth. Do the test multiple time at different moment of the day. The best results are usually during the night, after midnight. If you have optic fiber, the difference should not be so big.

If the ping is bad from this point, no materials in the home would fix that unfortunately.

For gaming, it’s better to rely on wired connection than wifi. Even more if the wifi is bouncing from wifi relay to the modem.