Cable from ONT to Router and Phone

[!!..PD..!!]

In your ONT,
1) Yellow patch cord is the input from BSNL which turns on the PON light. It should get stable when patch cord is inserted.
2) RJ 11 port is used to connect your landline. Phone light is the one which should be on when you set up the voice profile in your ONT. The light turns on when the configuration is correct and landline number gets registered online. It doesn't matter if landline phone is connected or not.
3) RJ 45 (ethernet port) is the one which makes internet work on your PC/Laptop.

@kreacher What is the exact issue here?

The black fiber comes in from BSNL/LCO to your home and then it is split in a box wherein its spliced to the Yellow patch cord.

There is no reason for Ethernet cable to be split and splitter is not required for FTTH connection.
Splitter is used for ADSL connection where a copper telephone cable comes in to your house.

 

[kreacher]

Sorry. the second image seems to be cropped while uploading.
The grey phone line and blue LAN cable both are connected to same LAN wire.

 

[sloj]

But what is the point of doing that, they have to add another termination for phone on the other end of the cable. Just remove the current setup of cables and get separate ones for both phone and ethernet and connect them independently.

 

[!!..PD..!!]

@kreacher, I agree with @sloj. Just buy one RJ-11 telephone cord and one CAT-6 or above RJ-45 ethernet cable from Amazon/Flipkart with free delivery (over 500) if you don't have them.

I already told you their purpose with ports. So you can just attach the new ones and you'll be good to go as long as the ONT has been configured correctly.

 

[kreacher]

Thanks everyone for your help. I replaced the existing CAT5 cable with a CAT6 and RJ11 cable.
Now getting 125Mbps on speed test instead of 95Mbps earlier on Fiber Value plan.

 

[!!..PD..!!]

You should get more if your plan is 150 mbps. Try to tweak some stuff in your ONT. Let it go if 125 mbps is enough for you.
BSNL usually provides 10 % more bandwidth than the plan offers. I get around 55 mbps on 50 mbps plan and I used to get 110 mbps on 100 mbps plan.

 

[kreacher]

I have the Fiber Value OTT with upto 125Mbps speed. Upload was 128Mbps on speed test.

 

[!!..PD..!!]

I thought its 150 mbps as you mentioned in the beginning.
Good then. You're getting promised speeds.