@Mr_Whatsittoya 

Try changing your DNS servers to something else like Googles:

Primary: 8.8.8.8

Secondary: 8.8.4.4

@Tony 

I've actually been using Google's DNS.

@Mr_Whatsittoya 

The router time settings may be causing it, go to Advanced > System Tools > Time Settings, select the option "Get from PC", and Save it. Now check the DDNS and firmware.

@Tony 

Checking the router time settings, I found that they were incorrect (more on that later).  I made the changes, saved the settings, and tried to check the firmware again.  No success.  I still get the following error:

Unable to connect to the cloud server. Please try again later.

With TP-Link selected as the dynamic DNS service provider, I still see the following error:

DDNS Unavailable

When I try to log in to the TP-Link Cloud from the router with my TP-Link ID, I still get the following error:

Request timed out.

I saw a different thread on this forum suggest to log into the TP-Link Cloud website (tplinkcloud.com) to see if their account was working correctly so I did that.  I do understand that the site is for managing TP-Link cameras but my account was accessible.

I was wondering if the problem could exist between the router and my cable modem.  I'm using a Netgear CM1150V and my service provider is Comcast (xfinity).  Unfortunately, there aren't any user-accessible settings.  It doesn't even appear that I can update the firmware.

Knowing the architecture (Archer C5400X > Netgear CM1150V > Internet), could the router be configured incorrectly?

Oh yeah, about the router's incorrect time...I have the router scheduled to reboot weekly that's when it appears the time gets desynchronized but I am able to manually synchronize the time via local PC or internet.

@Mr_Whatsittoya 

The cable modem looks to be just a typical modem. The manual mentions connecting an Ethernet cable from port 1 of the modem to the router. Not sure if that helps, but saw that mention.

As far as the router, try to activate the cloud function where you get the various errors you mentioned. Look at the router system logs, are there any mentions of what might have happened?

The TP-Link Cloud function failing usually comes down to the WAN DNS or time settings getting in the way. 

The other two things I can think to try is to factory default the router (if not done so already), and to re-upload the latest firmware on the router.

nieXas wrote

I have same problem, were you able to fix?

I wasn't able to fix it.

Same problem here. I've tied upgrading and downgrading firmware, and no use.

@EmailJim 

Are you able to check for firmware updates within your router?  I cannot and this is what I see:

Unable to connect to the cloud server. Please try again later.

I'm also not able to log into the TP-Link Cloud to enable the TP-Link DDNS.  Attempting to log into TP-Link Cloud results with a timeout error and using TP-Link as the Dynamic DNS service provider shows "DDNS Unavailable".

It almost seems like my Netgear cable modem is not allowing my TP-Link router to access the internet even though all devices on the network don't have any connectivity problems.  It's like direct requests from the router are being blocked.

Here are some of my IP addresses:

WAN IP address:  67.xxx.yyy.110 (submask 255.255.255.0).

Netgear cable modem:  67.xxx.yyy.1

TP-Link C5400X:  192.168.0.1

LAN IP address pool:  192.168.0.100 -- 192.168.0.199

The C5400X is configured in Router mode because the cable modem is only providing a basic internet connection.

Is anything odd about this?

@Mr_Whatsittoya no, I can't update from the web UI, only by downloading the firmware file with my computer and using the "browse" feature. I receive an error message that my device can't be identified.