System A has problems, where it will fail deterministically in a random 10% subset of cases.
System B has different problems, where it will fail deterministically in a different random 10% subset of cases.
Assuming the problems in each system are independent, the chance that a particular failure mode affects both system A and system B is only 10%*10% = 1%. Thus, the chance that a problem which occurs in system A, is gone when you switch to system B, is about 90%.
And that's why replacing your broken wifi router with a different wifi router usually makes your problem go away.