I have three lights that I need to sync.
Two of the on esp8266, one on esp32.
I had some time drifting issues on v 0.12, which I reported on github. The suggested solution was to go to 0.13b4+, and use network DDP, I tried searching the documentation about what that is, but I don’t see any information there.
I just want a colorloop effect, but setting it up on 0.13b4 is even worse, previously the sync went out over time, now it is completely out of whack on all three. The picture below is colorloop in sync, which is not in sync 
DDP is live network light protocol intended for synchronised displays.
The idea within WLED is to have one master WLED instance that has multiple virtual LED strips connected over network using DDP. This would be the same as having multiple physical LED strips connected to a single ESP chip.
When you set up virtual LED strip you do it in the same way as you do it for physical, but instead of choosing WS281x (or some other LED chip) you select Network DDP RGB and instead of entering GPIO (pin) numbers you enter IP address of slave WLED.
You do that in the LED Settings page as usual.
After you have done the set-up of virtual strips for all of slave devices (WLEDs on separate ESPs) you will be able to control them as segments or one (very?) long LED strip.
If all of your WLEDs are using 0.13-b4 or later you don’t need to do anything on them but if you are using older versions you need to enable DDP protocol in Snyc settings.