@Richie0414 

Using the backup hub H200, as suggested in a Reddit thread, doesn't work

I have 4 x C425 as well as a ton of other Tapo devices all connected to the same network.

The C425 randomly go offline with the red led instead of the green.

Checked all your router suggestions, which were not an issue, and installed a H200 as a backup hub. Went into the C425 settings and set the H200 as a fallback.

Well the C425 still are going offline and are not falling back to the Hub.

Same problem. I have 3x C425 and 2x C520WS. Only the C425 cams go offline sometimes but if I go to the Deco app, they are still connected with a strong signal.
I think the problem is inside the last C425 firmware

  @Richie0414 

I have exactly the same and it's disaster support we get here from TP-Link

Exact same problem here. I have 2 x C425, both with solar charging panels. Both are running latest firmware 1.2.23 Build 241119 Rel. 70306n. One installed in the driveway and one at the patio. The one at the patio keeps getting offline every week. All the configurations are exactly the same. The only difference I can tell is the one in the Patio receives less sun and therefore is not 100% charged. The patio also receives a stronger WiFi signal (-46) than the one in the driveway (-38). 

  @teddychu822 

hello

actually, tp link issued a new firmware but it seems like they don't make it available to all cameras yet. Only 1 of my 4 c425 has been updated with firmware 1.2.24 build 250103.

The objective of this update was to fix the issue we all have and so far, it works perfectly fine. 
our problem should be in the past soon! Hang tight

I have 1.2.24 on one of my 4 C425's, will see if it goes offline. Weird, the one with the latest firmware is experiencing sudden battery drain for no reason. I have it in full privacy mode so it's not due to over activation.

Actually, I been experiencing the drain issue with the older firmware as well.

  @paulpjred1 where did you got the new FW? He's not showing me any in the app. Thinking to send them back and request money refund. Had before another brand never issues. 

  @Schugi 

they are rolling it out. Be patient and it will be made available to your c425 as well. 
only 1 of my 4 has received it this far

Yes I queried this before with TP-LINK, they roll out firmware gradually, I think by Mac address.

Had another C425 go offline this morning, a V1 hardware,  V 1.3.11 build 241025 Rel.73923n. Wifi network shows as not connected, and it didn't fall back to the H200 hub.

Have had V1.2 go offline, but the V1 goes offline more often.

I've noticed the offline issue seems to happen more when I try to access the camera, then it sits there trying to connect, then it eventually goes offline.

When you walk in front of the camera, a solid red light is showing. After walking past the camera, and the red light showing.

I checked the App and it came back online and showed as connected to the H200. Even though the led was solid red, it actually recorded the event.

Now, was it the triggering of a recording that brought it back online, or was it just a coincidence??

Hope TP-Link can use some of this information and solve this issue.

  @Richie0414 

I have the same issue with my pair of C425 cameras.

I set up a separate 2.4 GHz Wi-Fi network for them to ensure they don't switch between 2.4 GHz and 5 GHz on the main network, but the issue still persists, which is really frustrating.

One of them 1.2.24 firmware and other 1.2.23, so one of them got the latest firmware mentioned in other comments and even that camera still goes to offline.

Both cameras are 3~4 meters away from the router.

I also contacted TP-Link support three time, but they don't seem to care about their poorly made product.