EDIT FINAL FIX : culprits of these lags is network adapter power saving mode. And Flow Control setting. For realtek lan enter driver settings in device manager → Advanced → Power Saving Mode to Disabled and Flow Control to Disabled.
Edit : second culprit is Flow Control setting in network adapter in windows, disable this
1.disable power saving mode in network adapter in windows. For realtek lan enter driver settings in device manager → Advanced → Power Saving Mode to Disabled. This alone fixes these longest many tens of seconds lags. Others settings in windows does not regulate this.
If you still experience some shorter lags, do the following changes also:
2. Disable offload and receive side scaling settings in network adapter. Offloading also causes connection to wow to worsen in some situations. But this recovers much faster than from power saving mode.
3. disable Boss Text Warnings, or hide when not targeted - this looks bugged on some bosses and can cause lag
4. in-game Low Latency Mode to Disabled - nvidia reflex increases these lags for some reason
I expect this will help many people, because I see these lags happen for others quite frequently.
Do people here have no problems with these network settings on their adapters while playing wow ? maybe wifi adapters regulated by windows better ?
Detailed Description of how this bug behaves : game responds, you can open bags, can enter game menu, you can move your character. Just mobs and other players do not move. When abilities are pressed they display GCD animation. Cursor moves normally. Operating system responds normally. After some time, can be even tens of seconds but can be shorter, what happened during lag plays on screen at fast speed. Latency displayed in game client becomes large number, in thousands, during that lag and after. FPS displayed in game client is normal at time of that lag. No Errors in Windows event log. This happens sporadically, for instance in 1/5 m+ runs.