I have a problem where my UDP streams (for example VoIP calls) gets delayed for around 4-5 seconds once every minute, causing crappy voice quality during those seconds.

This happens when I'm on 2.4G and 5G (have tested to have mixed mode and only 2.4G and 5G, same results).

I wrote a small java application to test this, the setup looks like the following:

laptop (MacBook Pro (15 tum, 2019)) connected to tp-link deco m9 plus v2 wifi that are pretty close (0.5 meter). I also connected a linux server to the tp-link, with ethernet cable.

Then I started a small service that receives UDP packages on the linux server and I send packages once every 20 ms from my laptop (pretty much like a VoIP stream).

Here is output from the server:

2020-05-08 06:56:42: Average: 20, max: 23, min: 16, count: 50, count above 25ms: 0, count below 16ms: 0
2020-05-08 06:56:43: Average: 20, max: 24, min: 15, count: 50, count above 25ms: 0, count below 16ms: 1
2020-05-08 06:56:44: Average: 19, max: 161, min: 0, count: 45, count above 25ms: 6, count below 16ms: 30
2020-05-08 06:56:45: Average: 19, max: 145, min: 0, count: 51, count above 25ms: 6, count below 16ms: 36
2020-05-08 06:56:46: Average: 20, max: 145, min: 0, count: 54, count above 25ms: 7, count below 16ms: 38
2020-05-08 06:56:47: Average: 19, max: 132, min: 0, count: 50, count above 25ms: 3, count below 16ms: 19
2020-05-08 06:56:48: Average: 19, max: 24, min: 15, count: 50, count above 25ms: 0, count below 16ms: 2
2020-05-08 06:56:49: Average: 20, max: 24, min: 16, count: 50, count above 25ms: 0, count below 16ms: 0

"Same" output but from the client side (my laptop), a tcpdump shows that my packages are sent correctly (time wise)

(The clock is 2 hours behind on the server, it shows UTC, my laptop shows CEST (GMT+2))

2020-05-08 08:56:40: Average: 19, max: 24, min: 16, count: 51, count above 25ms: 0, count below 16ms: 0
2020-05-08 08:56:41: Average: 20, max: 24, min: 15, count: 50, count above 25ms: 0, count below 16ms: 3
2020-05-08 08:56:42: Average: 20, max: 23, min: 15, count: 50, count above 25ms: 0, count below 16ms: 1
2020-05-08 08:56:43: Average: 20, max: 24, min: 15, count: 50, count above 25ms: 0, count below 16ms: 1
2020-05-08 08:56:44: Average: 19, max: 24, min: 15, count: 50, count above 25ms: 0, count below 16ms: 1
2020-05-08 08:56:45: Average: 20, max: 23, min: 15, count: 50, count above 25ms: 0, count below 16ms: 2
2020-05-08 08:56:46: Average: 20, max: 24, min: 15, count: 50, count above 25ms: 0, count below 16ms: 1
2020-05-08 08:56:47: Average: 19, max: 24, min: 15, count: 51, count above 25ms: 0, count below 16ms: 1
2020-05-08 08:56:48: Average: 19, max: 24, min: 15, count: 50, count above 25ms: 0, count below 16ms: 1
2020-05-08 08:56:49: Average: 20, max: 24, min: 15, count: 50, count above 25ms: 0, count below 16ms: 1

As you can see in the output on the server, the packages gets delayd and whatnot on the server between 06:56:44 and 06:56:47, so for around 4 seconds, this repeats itself once every minute.

I've tested with another wifi router and I don't get the same problem there.

Whats up with that? What are the deco doing once every minute that screws up my UDP streams?