No, they will be fine. Keep zigbee at 25 to avoid wifi interference. Keep wifi on 6 or below.
The Zigbee devices will change over to the new channel - it takes a while (mostly due to the sleepy aspect of battery powered devices).
takling the batteries out and puttng them back in would work to spee it up.
ok. just changed to 25 from 18 now.
Let's see if they will all come to that channel eventually. Because yesterday after changing from 20 to 18 I had to rejoin some aqara devices. And it is not fun 
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Actually, Samsung acquired SmartThings in 2014 
.
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I've changed to channel 25.
Contact sensor still does not go beyond "initializing"
And also now on channel 25, my 2 presence sensors do not join.
I have 3 hubs. The C5 was fresh (no devices)
I tried the contact sensor on the C5 now. It immediately detected and added the contact sensor.
C4 is the old hub. It also can detect and add the contact sensor.
Only the new C8 can't add it. It is stuck in "initializing"
I believe there is an issue in the database.
Previously there was an option to cleanup the database and shrink.
Now I can't find it. Is it removed ?
what should I do now ?
at channel 25 , 2 of my 3 presence sensors do not join zigbee.
Should I go back to channel 18 ?
pull the batteries wait one min and put it back in... If not re pair it to zigbee.
is this for presence sensor ?
I already did that maybe 20 times. (battery out , in) without any result.
what do you mean by "re pair it to zibee" ?
I am already trying to join this device to zigbee.
factory reset and re pair to the hub
I have one of those contact sensors on my C-8 and it has been working perfectly since the C-8 came out. Try rejoining it near a Samsung plug if you have any. You could also try increasing or decreasing the power level of the Zigbee radio to see if that helps. I would try dropping it to 4, try to pair the sensor. If that doesn’t work, increase it to 16 (the original default setting) and then try pairing it.
that was what I already tried more than 20 times.
OK. I will try lowering power now. But actually on channel 18 it was working fine (until I changed to channel 25 as advised here)
neither lowering power to 4 , nor increasing it to 16 did help.
So I changed back to channel 18
The presence sensors were detected immediately.
There seems to be a problem on channel 25
These presence sensors maybe do not support that channel because all of my other devices were OK (except the device in the subject) at channel 25 (including 1 presence sensor which is slightly different)
Some older Zigbee devices definitely do not like high numbered Zigbee channels. That is why I have always used Zigbee channel 20, as it avoids any interference with 2.4 GHz WiFi, as long as your WiFi uses channels 1, 6, or 11 (with 20 MHz channel width.) When I migrated from SmartThings to Hubitat back in February 2018, I discovered that some of my SmartThings Zigbee sensors would not pair on Zigbee channels above 20.
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actually I have 2 types of Smartthings arrival sensors. Probably purchased in 2 different times, their plastic casing exactly same, but inside circuit is a little different.
Type 1 does not join channel 25 at all but can join channel 18 immediately
Type 2 immediately joins channel 25 , and can join channel 18 with some difficulty.
weird ?
@ilkeraktuna the problem with 18 is Wi-Fi interference. As @ogiewon suggested try 20.
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If they are two different generations of the ST arrival sensor with different circuit boards, then not that weird IMO.
It would be weird for two identical devices to behave differently with respect to zigbee channels.
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Ok. On channel 18 now my presence sensors are working.
I just have one issue, which is in the subject of this thread:
One of my motion sensors do not join the hub.
It gets stuck on "initializing"
But it can easily join my other 2 hubs (C4 and C5)
I believe there is something on the DB of C8 which prevents the sensor join.
Maybe it is because I did something wrong on my initial attempt.
How can we identify the problem ?
