hello ive upgraded my network with a tplink ax1500 router and im getting inconsistent high ping in videogame now? doesnt fluctuate its either 90-100 which is normal for me or 230-240 and just sits there. this occurs randomly throughout the day, sometimes i log in to the game its normal, sometimes it high. tested with my old tplink wr740n im consistenly getting my normal 90-100 ping. i dont really understand why a router affects this? my network setup is:

my isp issued ftth router -> cat 6e cable -> new ax1500 router -> cat 6e cable -> my pc

again if i replace ax1500 with wr740n ping is normal and also if i completely bypass 2nd router (that is ftth -> cable -> pc) ping is also normal

thanks