Here is definitely NOT the support desk from EUFY.
You find this on the EUFY-website. 
Eufy Doorbell is Offline and will not re-connect
I now and i have already made a ticket a few days ago.
I’m just asking here if anyone has already gotten a solution from Eufy for this problem.
You could also use the magnifier (search option) in the right upper corner to get a better answer tor your issue.
There are more users that had the same problem as me.
Tech support only asking the same questions over and over again about the internet connection.
It’s in my opinion not the internet connection but the bad software.
I have a good and stable connection and still the doorbell go’s a few times a week offline.
The software will not reconnect but the users has to do that manualy every time.
A getting crazy about this device because when it go’s offline there is no massage and when someone stands at my door and the bell is offline and don’t now that.
Do you have the battery doorbell or powered? Some instances of it going offline has to do with lack of power coming in
just emailed them this My kit all eufy crap
3 doorbells none more than 20 feet from a base keeps losing signal TOTALY UNFIT FOR PURPOSE
2 x 2k cameras ONE THAT
1 ptz camera ISONLY 8 FEET FROM BASE SEEMS IT WORKS MOST OF THE TIME
2 x base 2
CONCLUSION
your kit is useless for anyone that lives in a house with doors that they close
the experienced range is
8 feet for staying connected 80%
over feet with door closed FU*****ing forget it
WHAT IS YOUR SOLUTION TO GET THIS LOT WORKING RELIABLY?
It’s sad that, after a year, this still isn’t solved. We have laptops, smartphones, a tablet, a google home speaker, a philips hue bridge and our heating, all connected to the wifi and everything works perfectly. When something goes out of range, it reconnects when in range. Even our Eufy security cam keeps its connection.
Everything except the Eufy doorbell.
Any decent programmer would make a product that tries to reconnect after it loses connection, but not for this doorbell.
I tried everything, fixing wifi channels on all possibilities (1-6-11), putting the bell next to the homestation, etc. Nothing helps. What improved it slightly is connecting the homebase itself via wifi instead of wired, but it increased stable connection times from 1 day to 3 days, give or take. But then I still need to bring the bell inside and try to reconnect it. Which it completely refuses now, so we have to send the unit back.
72 replies and many posts on reddit and elsewhere about this issue. Absolutely frustrating that there is no fix for this. Just a simple firmware update where your doorbell just automatically resynces would be an easy fix but they don’t care. I was allowed to return the bell after almost a year and it feels such a relief to be done with this product. Its unfinished and just terrible that they haven’t fixed this. I am now looking into different brands. So happy I got my money back. Worst buy ever! Usually anker products are good but not this one
I have the same problem that my doorbell kept disconnecting and disapearing from my device list.
After reading these posts I came across somebody that wrote about the top screw in the holder you mount on the wall.
As the provided screws are crap I used my own and they didn’t fit as nicely as the original once. The top screw was not totally flush and my guess is it touch the sync button on the backside of the doorbell. I was able to screw it in a bit more and now it was flush.
After remounting the doorbell is stayed connected. It has been a week now without problem, before it went away between a few minutes and a few hours, a day. One time I noticed the doorbell beeped before disapairing, just like when connecting to the Homebase. So I think this might be the solution for part of the problem discribde here.
Interesting!
But true.
If you use other screws than the originals of course these could cause damages and malfunction.
I’ve also had the problem of the camera loosing connection with the Homebase. I did use different screws, but that wasn’t the problem. I contacted support and they told me to go to the Homebase settings in the menu, go to “Working mode” and select the “Performance” option.
That did the trick for me, I haven’t lost connection for days now.
i have a weird one . with my wired doorbel
after few months battery was getting low out of nowhere .
then i fixed is and now it goes ofline if its wired and wont reconnect.
then when i unscrew the wire’s it pops back online 
and i checked i have 24V and 40VA so it should work perfectly
May be you can ask your question on EUFY’s forum.
Maybe it will help somebody here.
- I saw such a sync issue when my homebase were switching from lan to wifi to lan few times. So, I only configured the homebase to use Lan. (Wired ethernet)
- Battery + power issue: The doorbell needs ~10W of power to properly charge. So, transformers of 8v and 0.5Amper like shown above are too weak. This will output only 4W of power, so doorbell might run of battery. I am using 8v, 1A transformer (8W) which does the trick.
Can someone please help i have a eufy 2K wired videocam this is the second day that it’s gone offline ive rebooted my router, restarted the hub disconnected and reconnected the hub, pressed the sync button. Nothing is getting it back online No support at the weekend
I have a Video Doorbell E340. Everything is good for 1.5 months until Nov 28, I started to lose connection to the doorbell. From the Eufy app I cannot see a live video.
I doubt it’s some software issue because I saw there is a software update on Nov 27.
You should contact the support asap.
Not clear what you mean with 1,5 months and November 28.
I mean the doorbell worked for one and half months until Nov 28.
I just tried to uninstall the doorbell from the wall, remove the device in the App and re-add it. Now it becomes a bigger problem: the doorbell cannot be added any more. There is no “beep” after I hold the SYNC button for seconds. I can neither add the doorbell through homebase nor through wifi.
Sent an email to eufy support team. Really disappointed about this product. I have another eufy cam 2 pro which completely die after 2 years (cannot be charged, cannot be synced/re-added to the app).
So its under warranty.
You should contact the support with all data from you item.
Best is is to add a video.
I am having this same issue with my Eufy doorbell going offline frequently. I contacted Eufy support and after getting conflicting information this is their final response - due to regional reasons they are unable to even offer an apology???
Dear Customer,
Thank you for your patience.
We have released a new version to solve the doorbell offline problem some time ago. However, if your device is still not resolved after pushing the new version, we are very willing to provide you with a warranty. Unfortunately, we cannot deliver to Australia, so we are sorry that we cannot provide you with further assistance. We are happy to provide you with a discount. Unfortunately, we cannot provide discounts on the Australian official website. I am really sorry about this.
Unfortunately, due to regional reasons, although we would like to offer you a discount and express our apologies, we are unable to do so.
We once again deeply apologize for the inconvenience the product has caused you and have a nice day.
Reference TicketTNQ411835995 if contacting a CSR
Shane
Eufy Customer Support Manager