If it was fine then nothing changed then almost certainly it's due to the holidays - the usual peak time congestion you'd get with your ISP will become more prevalent over longer periods of time as people take time off for the holidays, likewise server load for the games you play will increase as well and so that could be it. Play direct to your ONT, you'll have no devices on your network that could affect you so it'd just be the ISP and game that are factors, if you experience the same issue then one of them will be the cause. If it's the game the only thing you can do is force servers you wouldn't normally, their ping may be higher but it may also be more stable.
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