https://www.youtube.com/watch?v=DN6gvMoKlL4

 

First some comments on the above URL:

You may follow the above official video link on how to connect your Deco to Singtel
You may substitute Modem for Optical Network Terminal (ONT) in the above video (Not sure if Singtel is still giving out Modems)
One thing to remember: You may be able to use only LAN1 port of the ONT

 

1. Connecting Deco (Router mode) to Singtel ONT (with Singtel Router in between)

 

I do not know if the above link sets up the Deco in Access mode or Router mode - read somewhere that (TPLINK  or Singtel - do not know who) Customer Support insists it  should be access mode only. But you may be able to use it in Router mode if you are NOT going to connect Singtel TV set-top box to the Deco.

 

Why router mode? There are certain features which do not work in access mode (you can see the explanation in the app for the features not supported in access mode). It was also that TrendMicro protection (if bundled with Deco) did not work in access mode on older firmware (hopefully this is fixed now).

 

Details

My Plan: Singtel Fibre Home Bundle (Fibre Broadband + Home Digital Line)
Singtel TV: No (Surrendered)
Singtel Wifi Gigabit Router AC Plus
Deco model: M5
No. of units: 3
Firmware version: 1.7.3 Build 2023-009 Rel. 59213 (latest)

Deco app: v3.6.34 (latest)

 

Physical Setup: Singtel ONT LAN1 <---> Singtel Router <---> Deco M5 (Main)

 

On the Deco app:

a. More > Internet Connection

Internet Connection Type: You may leave it as Dynamic IP  
(OR)
Set it up as Static IP with an IP from the Singtel Router's DHCP range; In this mode you can specify the DNS servers you want to use e.g.: google 8.8.8.8/cloudflare 1.1.1.1 

If you have made modifications: Save

 

b. More > Advanced
Operation Mode: Wi-Fi Router

IPTV/VLAN: Disabled (yes, that is correct - as there is no Singtel TV)
Save

2. Connecting Deco (Router mode) to Singtel ONT directly (No need for Singtel Router!)

 

Yes, this is indeed possible but this does have a major problem unfortunately.

 

Until a few days ago (Time of writing: Dec 2023), I had this setup running for more than 2+ years (along with a port designated for Singtel TV on one of my Decos even though I did not have Singtel TV). 

 

Eventually I had to dismantle this setup since I could not make it work anymore (though this is my preferred setup as I do not need an extra device in between)

 

What is the problem?
Once you get it working initially, it can continue to function without any issues until you reboot the Decos. But once rebooted, the main deco may not be able to connect to Internet at all. It gives a message 'No internet access or no WAN IP obtained' 

 

In such a case, you will have to fall back on the Singtel Router and start all over again (if you had a working setup before, remove the other Decos first)

 

For example, the following situations require the reboot of the Decos (and you may face issues with Deco after that): 

• Firmware upgrade
• Fix issues with some devices not able to connect to wifi (which requires a reboot of all the Decos btw)
• Physical re-organization of the Decos without any config. changes

 

Sidenote:

Sometimes it (reboot of all Decos) works without issues and at times it does not (even powering off everything including ONT, multiple times) - I had varying degrees of success and there is no sure way to make it work. 

 

How to set it up anyway (updated after initial posting)
Set it up as shown in the video with Singtel Router in between. You may need to leave it running for a few hours.

 

Then:

• Switch the ONT connection from Singtel Router to Main Deco
• Operation Mode: Wi-Fi Router
• Change Internet Connection Type to 'Dynamic IP' (it might take a few seconds to switch if the previous setting was different)
• IPTV/VLAN: Enabled, ISP Profile: Singapore-Singtel. Also, select a port for IPTV. The app has a possible bug: If it shows only one port (port 1 whereas we are supposed to select the other port for IPTV), select that. Save.
• It will try to save the new config. but will fail. If you try to reboot the main deco, that will also fail
• Remove the Power for the main deco & wait for a couple of minutes
• Power on the main Deco
• Try the IPTV/VLAN config. again. This time it will be able to Save. For me, this somehow brings the internet back online on the deco magically after a few seconds. But if I try to get smart and try these steps without the Singtel Router, it never works :-( 
• (If the internet connection still does not come up after a few attempts, it may be a good idea to give up on this setup)
• You may turn off the Singtel Router 
• Once everything is working, add the other Decos. Then you can select a port for Singtel TV on other Decos as well.

 

Possible guess on why this issue is happening (only speculation as I have no way of knowing):
1. I noticed the Singtel router gets a static public IP (WAN IP) but without any netmask/gateway/other details. This could be confusing the main Deco (but works well with the Singtel Router).
Update: Following the above steps today, I could get the internet connection working on main Deco once. I examined the WAN IP details (from Singtel) and they are in order (with netmask/gateway & DNS Servers). So this looks more of a problem with Deco (than Singtel not supplying the correct IP details for the WAN interface)
2. It is also that the static IP that Singtel assigns varies (changes every few months?). Possibly this could explain why the Deco was working at times after reboot (when there is no change) and whenever there is a change in the IP (comes into effect only after everything is powered off), it does not connect at all.

 

Perhaps someone from TPLINK can work with Singtel and sort this out - though I am not pinning my hopes on this. I did have a TPLINK support request raised a few months back on this issue but it did not go anywhere.