I occasionally shoot H.S. gym basketball, and have a friend who shoots H.S. volleyball. When we get to talking, this is what we complain about; all of them are lighting related.
1) The different types of lighting make it hard to set the white balance. Especially difficult is the cycling of the sodium or fluorescent lamps. ie. 60Hz cycling makes for some underexposed shots if you catch the off cycle. The 7DII has a setting to delay the shutter to release only on the "up cycle" if yours is a II.
2) As you're discovering dim lighting/and fast motions make for difficult shooting. f2.8 can work if you're prepared to do considerable post processing to remove noise.
What my friend has resorted to is shooting an 85 f1.8 and cropping aggressively to get tight (he's shooting a 1DX full frame). He also shoots an 85 f1.2, but that lens wasn't made for fast action. He says it can work for volleyball because the action is predictable, allowing him to pre-focus and camp out on a spot. Even then his keeper ratio is less than 30%.
I borrowed his 85 f1.2 to shoot a local Sporter Air Rifle Match (another sport with challenging lighting, but no fast action). Makes for some interesting shots. I'll see if I can share some.
