Hello i had the problem with high peaks ping, lag and disconnection, at first I thought that the fault was of ESO's servers, others games (no MMO) worked fine, the download and upload worked fine etc, but the problem was in my pc or modem/router. i used an internet test to measure my ping and i was having the high ping peaks all the time so it wasnt eso servers. In the end i solved it using Leatrix Latency Fix. Now my connection works fine and my ping is back to normal and have no lag.(except Cyrodill of course haha)
Maybe this can help some of you who have similar problems
Link to an internet test for ping
https://www.meter.net/ping-test/
Link to Leatrix Latency Fix
https://www.wowinterface.com/downloads/info13581-LeatrixLatencyFix.html