Because of what can be a wild ping on a laptop via wifi when the tablet is connected to the same network?

Question

WiFi

Actually, the situation.
There are 2 routers: Zyxel Keenetic II and Xiaomi Mi Wi-Fi Router 4C, this glitch is observed on both.
The essence of the glitch: wifi is up on the router. The laptop is connected to this wifi network, everything works fine, the ping is minimal. One has only to connect a Lenovo tablet to this router, as the ping jumps into the ceiling and always exceeds 1000 ms. Firewood in the laptop is changed, wifi adapters tried different ones, the effect is preserved.
What could it be and how to deal with it? (I don't want to throw away my tablet yet)