I finally found the cause of the lag I started experiencing recently with GW2 and looking at how many people are having this, it might be that they have the same issue I had.
let's start from the beginning.
I opened a ticket with GW2 support that was very nice and really tried to help.
Run all the tests they asked and sent all the report, then after an email with a possibile solution (Winsock Reset) I found out what was the issue.
right after I resetted the Winsock as explained by Jarbyn from support (<3) I noticed the game became playable again, so I connected my new bluetooth earphones ( Soundpeats Truwings on bluetooth 5) to keep playing a bit.
As soon as I did that the lag came back with ping on 1k+. I thought immediately that was weird but actually possibile! I thought I had to test to be sure it was the bluetooth.
Checked on Google and with my surprise I found many references online about people having bluetooth interfering and slowing down wifi connections even on phones (I am on laptop).
Suggested solution was to use Channel 1,6,11 on the router (2.4ghz) as they are more stable channels.
So I decided to test that.
Here in Italy was around 1 a.m. and Tequatl was about to come, so I thought it would be a perfect testing ground.
Started with Channel 11 and ping was between 200-400 (better than the 1500 ping spikes I had with bluetooth + wifi on channcel 13 - the less busy channel I have), switched to channel 6 and was around the same. Channels 1,6,11 did not make much difference, but leaving router on auto channel selection was better with ping between 50 and 130.
Then I switched bluetooth off and TA-DAA! ping between 48 and 88
I believe another solution would be to pass to the second wifi at 5Ghz as bluetooth uses 2.4Ghz, there should be no interference at all like this.
I hope this might help people that have the same issue!