@szabolcsdekany I have the same issue, the jitter is horrifying. It swings between 5ms and 1000+ every few seconds. It make video conferencing and online gaming impossible. I can't believe tp-link ship firmware which such a huge flaw. Trust me I have fully tested my entire connectivity and its definitely the tp-link x60's at fault. I am so annoyed, after spending £650.

@szabolcsdekany same problem with Deco P9. I just realized when I read your subject and try to close my P9 MESH 5ghz. I switched 2.4 ghz and my connection is better now. When I turn on 5ghz all messed up. I am waiting for replies from community and devs.

@hugo20 Hi, if you hear anything from Tp-link I would be grateful if you could let me know on here if possible. Thanks for you reply and suggestion, much appreciated. 

In my P9 Mesh , I updated with 20210115 debug zip file manually. Yes when I turned off 5Ghz and only 2.4Ghz I can get good result on the speedtest. I will write different results on Iphone 7 Plus. Test position 50cm from main P9.

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Scenario 1 2.4 Ghz : ON 5 Ghz : OFF Mesh: OFF BEAMFORMING: OFF Results: 78,7 Down, 8.02 Upload ,6ms Ping, 1.1ms jitter

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Scenario 2 2.4 Ghz : ON 5 Ghz : OFF Mesh: ON BEAMFORMING: OFF Results: 82,3 Down, 8.05 Upload ,6ms Ping, 0,98ms jitter Scenario 3 2.4 Ghz : ON 5 Ghz : OFF Mesh: ON BEAMFORMING: ON Results: 88,9 Down, 8,12 Upload ,6ms Ping, 0,6ms jitter

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Scenario 3 2.4 Ghz : ON 5 Ghz : ON Mesh: ON BEAMFORMING: ON Result1: 89,2 Down, 8,17 Upload ,17ms Ping, 100ms jitter Result2: 91,8 Down, 8,09 Upload ,12ms Ping, 25ms jitter Result3: 86,6 Down, 8,11 Upload ,20ms Ping, 25ms jitter Note: when the speedtest beginning ping values changing too quick 100-95-27-12 like. This is I realized.

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Scenario 4 2.4 Ghz : ON 5 Ghz : ON Mesh: OFF BEAMFORMING: ON Result1: 78,3 Down, 7,98 Upload ,7ms Ping, 43ms jitter Result2: 78,7 Down, 8,07 Upload ,8ms Ping, 10ms jitter Result3: 91,3 Down, 8,08 Upload ,7ms Ping, 22ms jitter Note: same unstable ping values occur when test starting.

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Scenario 5 2.4 Ghz : ON 5 Ghz : ON Mesh: OFF BEAMFORMING: OFF Result1: 94,0 Down, 7,95 Upload ,8ms Ping, 12ms jitter Result2: 87,2 Down, 8,1 Upload ,12ms Ping, 17ms jitter Result3: 79,9 Down, 8,11 Upload ,13ms Ping, 51ms jitter Note: same unstable ping values occur when test starting.

Scenario 6 2.4 Ghz : OFF 5 Ghz : ON Mesh: OFF BEAMFORMING: OFF Result1: 59,7 Down, 8,17 Upload ,8ms Ping, 53ms jitter Result2: 93,1 Down, 8,31Upload ,9ms Ping, 11ms jitter Result3: 91,3 Down, 8,08 Upload ,9ms Ping, 36ms jitter Note: same unstable ping values occur when test starting.

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.Scenario 7 2.4 Ghz : OFF 5 Ghz : ON Mesh: ON BEAMFORMING: OFF Result1: 83,9 Down, 8,08 Upload ,12ms Ping, 67ms jitter Result2: 80,3 Down, 8,02 Upload , 19ms Ping, 88ms jitter Result3: 92,6 Down, 8,04 Upload ,8ms Ping, 20ms jitter Note: same unstable ping values occur when test starting.

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Scenario 8 2.4 Ghz : OFF 5 Ghz : ON Mesh: ON BEAMFORMING: ON Result1: 91,2 Down, 8,09 Upload ,9ms Ping, 84ms jitter Result2: 87,9 Down, 8,07 Upload , 11ms Ping, 24ms jitter Result3: 81,0 Down, 8,07 Upload ,8ms Ping, 19ms jitter Note: same unstable ping values occur when test starting. Its better now than old firmware. But still worse than last months.

@TP-Link 

1. Did the ping spike and unstable connection only happen to 5ghz on the Deco?

    It happens on both 2.4 and 5ghz 

2. Would turning off the Mesh technology of the device on the APP help or not;

    This does not seem to have any effect on the jitter levels being experienced

3. Please download a Wi-Fi Analyzer Tool on your cellphone to check the current wireless channel and wireless channel interferences around;

    See screenshots below...

Well after 24 emails with the support team, we had no resolution, they said that I have a perfectly stable connection and that ALL my devices are the issue not the deco.. despite providing proof that the jitter is there event when pinging the deco itself from several devices.

I'm very disappointed in the unwillingness to get to a resolution regarding this :(