In reply to a post by jpm:

The brown box on the wall outside your house is connectorised, check the light levels there. If they are low then disconnect your SFP and call in a loss of service and get VM back out.

I could do, i'm trying to be considerate with stuff im touching, just to prevent VM being a PITA if they know ive been messing around.

I am going to find a meter and test the fibre to the SFP, and then from the coupler see where the problem lies. I think its going to be the connector to be honest.

Aha OK the plot thickens. Yeah thru SC to SC APC couplers especially can be a right nightmare.

A lot of them are just cheap and horrible and you can see it when you replace a bad for a good one how much light that they can lose, even intermittent losses

If you have access to a calibrated light source and power meter, you should be able to do a loss test on your link.

My gut feel is that you're losing upwards of 10dB on your internal fibre cabling. It should be sub 2dB by rights if everything is good.

In reply to a post by Pheasant:

Aha OK the plot thickens. Yeah thru SC to SC APC couplers especially can be a right nightmare.

A lot of them are just cheap and horrible and you can see it when you replace a bad for a good one how much light that they can lose, even intermittent losses

Im pretty certain the patch lead from my SFP to the coupler is fine, its the same manufacturer we use for all our optical cables.

The cable im using is a LC to SC cable, to reduce the use of another coupler! - Then this cable is just coupled from the incomming LC/APC,

I highly suspect this coupler is bad, its a cheap one to be honest. Its nothing special

In reply to a post by Pheasant:

If you have access to a calibrated light source and power meter, you should be able to do a loss test on your link.

Good shout. I will give that a go!

I think the fibre is long enough bundled up to run it outside the door and connect directly in the brown VM box, but new coupler on the way and should be delivered today!

You can fudge your own loss test if you don't have a calibrated light source in your warehouse.

Take a reading at the VM CSP as @jpm suggests. Take another reading wherever your patch cable leads to. If there is any more than a few dB of loss it's your couplers and/or patch leads at fault.

In reply to a post by Pheasant:

You can fudge your own loss test if you don't have a calibrated light source in your warehouse.

Take a reading at the VM CSP as @jpm suggests. Take another reading wherever your patch cable leads to. If there is any more than a few dB of loss it's your couplers and/or patch leads at fault.

Give me a few hours, i shall do some testing!

I will keep you updated.

In reply to a post by Pheasant:

You can fudge your own loss test if you don't have a calibrated light source in your warehouse.

Take a reading at the VM CSP as @jpm suggests. Take another reading wherever your patch cable leads to. If there is any more than a few dB of loss it's your couplers and/or patch leads at fault.

The VM engineer said that to the router he had -12dBm, so im going to use that as a rough estimate of the incoming light level until i can test it.

In reply to a post by suttonscloud:

In reply to a post by Pheasant:

You can fudge your own loss test if you don't have a calibrated light source in your warehouse.

Take a reading at the VM CSP as @jpm suggests. Take another reading wherever your patch cable leads to. If there is any more than a few dB of loss it's your couplers and/or patch leads at fault.

The VM engineer said that to the router he had -12dBm, so im going to use that as a rough estimate of the incoming light level until i can test it.

Don't think you need to do any testing. You have your answer already (if the VM engineer was being honest with his light reading, and why would he like)

You have near enough 16dB internal loss which is how do I put this....mmm. Utterly horrendous 🤣

You should have no more than 1/10th of that.