This lag stops explosive weapons from killing zombies, however the explosive will still damage the zombie, they just won't die. Here's a guide to deal with RPG, MGL-140, SCMITR, or grenades lag. You have to fire enough explosive rounds to kill the zombie. For a devastator, you can't just shoot your RPG once then fire with your G17 and expect to kill it, you have to shoot it with the RPG until the health bar has gotten as low as it will go with the lag in effect. Taken from http://forums.mochigames.com/showthread.php/3743-How-to-cope-with-RPG-lag.
These are the musts to help you avoid explosives lag, make sure to bring a weapon that is...
- Good fire rate (if you can click fast, you can use a semi-auto, but it is not recommended)
These criteria for guns' are helpful, but not 100% necessary, it helps to have a gun that is...
- Fully automatic
- Able to pierce many zombies
- Have a short reload speed
- Have a large clip/magazine
Usually the damage per shot of the weapon doesn't matter, so many mid-level players use the MP7 and/or Desert Eagle. Keep firing explosives at the zombies until their health bars stop going down. (If they don't have a health bar, you only need to shoot them once with the RPG or any other explosive, at this point all those zombies have a HP of 1/∞ of a hit point. Then take the weapon you chose in step 1 and start shooting at the zombies you shot. It should only take one shot to kill them, even if your weapon is the Glock 17. Repeat from step 2 until all the zombies that you want dead are dead.