This kind of issue can be caused by numerous things. It can be the Unifi routing to your company's network, connection and firewall settings on your Unifi Dlink router (which you have extremely limited access to unless you reflash to dd-wrt), type of VPN protocol being used, etc. It's hard to say just based on what you've mentioned

VPN settings should not have to be altered just because you're using Unifi or Streamyx. If I had to guess I'd put the blame on the DIR-615 .. maybe you can try using a wired connection ?

Far as I know, DECT in Malaysia does not use anywhere near the same frequencies as wifi.

As for wireless channels, make sure to use 1, 6, or 11 and never any others.

If someone in your area is breaking this rule and using another channel besides those three, it can screw things up for you. Check the other strong networks in your area and if any of them are on non-1/6/11 channels, switch to a channel far away. For example, if someone is broadcasting a strong signal on channel 2, then channel 1 will be useless, so switch to 6 or 11.

@Sting Ray

To use your old Streamyx router with Unifi, you need to hook it up to your PC then log into its web configuration. Make sure you take note of the local IP address and subnet mask information that its been configured to use.. it should be on a different range than your Unifi (192.168.0.x/255.255.255.0 by default). If its on the same IP range as Unifi, change the routers IP to 192.168.0.2 or something so it doesn't conflict with the Unifi router IP. Then just disable its DHCP server and apply the settings.. Restart the router and wire its LAN port into one of the blue coloured LAN ports on your DIR-615 by TM. This will ensure that you only have 1 DHCP server running on your network (each router has a DHCP server).

Remember, by disabling DHCP it means you wont be given an IP address automatically when you plug in the router again. So to access its configuration page you'll have to set an appropriate IP address manually to be able to access its web user interface.

I can't really gauge how good you are at this so don't try it if you're not really sure about what I'm talking about ><"

if it is stable with wired connection it has nothing to do with Unifi.
apologies for butting in like this

turn off the n protocol of the dir-615. just stick to b/g. noticed it goes further and is more stable. Also don't use channel 12 and 13.

@Sting Ray

Sometimes, wireless connections tend to drop packets. Windows reports the link as still 'connected' but depending on the quality of the wireless link, if you tried to ping or send data across the network you would notice it timing out.

Different VPN protocols (and protocol configurations) are susceptible to a different level of network disruption.. so if this wireless connection were to be timing out for even 3-5 seconds perhaps the VPN client would assume the VPN server on the other end is not active anymore and close the link. This could be whats happening in your case.

@Sting Ray
if u use bought a local branded notebook with intel chipset, u are not able to scan channel > 11
those channel are not licensed to use in malaysia. but some AP/router still have those channels in their firmware.

those channels are used in japan etc.

IMO keep your copper line and just ignore this new number. because this phone wont work if you switch off the modem (no phone calls coming in if no electricity), wheres you old copper line works without electric.

I just went to my sister's house which they were installing Unifi for her today, her setup require the 'Black' cable from the phone pole / FTTH Box outside her house to be terminated at a Fiber Termination Box (which is a medium size white box slightly bigger than the one in your pic) on the outside wall of her house and then a 'white' cable with orange wording come out from it and go inside the house. They then connect this 'White' cable with orange wording to the Fiber Wall Socket (which i think looks like the one from your pic) and come out with the 'White' cable with socket connector to the Fiberhome unit. Is this a must ? or i can ask them to just directly do like yours and install without the Medium Size Fiber Termination Box outside my house ?

I did talk to them just now during install, they told me they pull the Black cable into the Fiber Termination Box then change to white cable because the Black cable is for outdoor use and cannot bend much, while the white cable is slightly less sensitive when you bend it, so it is more suitable for indoor use when u pull thru corner and conceal it in the plastic wire casing. What i didn't know was the 'Black' outdoor cable can be pulled straight into the FiberWall Socket directly without using the white cable. Btw, when u mention that you have the 'Black' outdoor cable pull straight into the Fiberhome Modem, you mean u still go thru the FiberWall Splitter like rizvanrp pic right ?

What about http://www.strongvpn.com  ? It's LPTP VPN any speed connection to UK/US server. Only RM7 per month 

They do have openvpn and better encryption but it will cost you more.

Yeah, its the one listed under the "High Speed Internet - Residential - xx Mbps" row on the printout slip

What is the login and password for the PPPoE? Today, after they install, they only gave me the Wifi password, they din even give me the login and password for unifi email. I was told that the unifi email (login and password) was not the same in the Router (dlink 615). how true is it?

Google DNS unblocks most sites but some have a HTTP level filter on them (totally drops all HTTP traffic), need to use an SSH SOCKS proxy/VPN for that as even a http proxy will not work

@sting

As in, when you attempt to connect to some sites.. the DNS resolves the correct IP and all but the site returns no data, just a blank page. Can either be a block by TM or by the site operator. But I think I've tested it with a HTTP proxy before (can't really remember) and it has the same results, which leads me to believe its a local HTTP filter done by the ISP.