Wanted: passive CWDM multiplexer

Hello,

yesterday I setup a new dark fiber (9.8km) and enabled the first optics (Fibre Store CWDM-SFP10G-20SP, 1330nm, 20km) which was recommended by fibrestore support for the attenuation information I sent them about both fibers which was given from me by the ISP.

The connection worked immediately when I put the optic into the switch, no errors nothing. Tonight, link flapping started. Now the link went offline.

• On switch A:

display transceiver diagnosis interface gives:

transceiver diagnostic information:

  Current diagnostic parameters:

  Temp.(¡ãC) Voltage(V) Bias(mA) RX power(dBm) TX power(dBm)

  35 3.24 33.21 -19.71 1.11

  Alarm thresholds:

  Temp.(¡ãC) Voltage(V) Bias(mA) RX power(dBm) TX power(dBm)

  High 90 3.80 100.00 0.00 6.00

  Low -5 2.70 0.00 -16.99 -7.00

There are some errors on this interface:

 Peak input rate: 204 bytes/sec, at 2018-08-17 17:10:41

 Peak output rate: 376 bytes/sec, at 2018-08-17 21:09:05

 Last 300 second input: 0 packets/sec 0 bytes/sec -%

 Last 300 second output: 0 packets/sec 0 bytes/sec -%

 Input (total): 68540 packets, 6552135 bytes

  41 unicasts, 104 broadcasts, 68284 multicasts, 0 pauses

 Input (normal): 68429 packets, - bytes

  41 unicasts, 104 broadcasts, 68284 multicasts, 0 pauses

 Input: 106 input errors, 0 runts, 0 giants, 0 throttles

  104 CRC, 0 frame, - overruns, 2 aborts

  - ignored, - parity errors

 Output (total): 124626 packets, 10398046 bytes

  50 unicasts, 1426 broadcasts, 123150 multicasts, 0 pauses

 Output (normal): 124626 packets, - bytes

  50 unicasts, 1426 broadcasts, 123150 multicasts, 0 pauses

 Output: 0 output errors, - underruns, - buffer failures

  0 aborts, 0 deferred, 0 collisions, 0 late collisions

  0 lost carrier, - no carrier

• On switch B:

display transceiver diagnosis interface gives:

transceiver diagnostic information:

  Current diagnostic parameters:

  Temp.(¡ãC) Voltage(V) Bias(mA) RX power(dBm) TX power(dBm)

  56 3.20 43.38 -11.59 1.02

No errors on the interface on switch B:

Peak value of input: 242 bytes/sec, at 2018-08-17 20:13:48

 Peak value of output: 440 bytes/sec, at 2018-08-18 03:23:23

 Last 300 seconds input: 0 packets/sec 0 bytes/sec -%

 Last 300 seconds output: 0 packets/sec 4 bytes/sec -%

 Input (total): 68628 packets, 5831800 bytes

  32 unicasts, 767 broadcasts, 67829 multicasts, 0 pauses

 Input (normal): 68628 packets, - bytes

  32 unicasts, 767 broadcasts, 67829 multicasts, 0 pauses

 Input: 0 input errors, 0 runts, 0 giants, 0 throttles

  0 CRC, 0 frame, - overruns, 0 aborts

  - ignored, - parity errors

 Output (total): 50717 packets, 6105567 bytes

  28 unicasts, 810 broadcasts, 49879 multicasts, 0 pauses

 Output (normal): 50717 packets, - bytes

  28 unicasts, 810 broadcasts, 49879 multicasts, 0 pauses

 Output: 0 output errors, - underruns, - buffer failures

  0 aborts, 0 deferred, 0 collisions, 0 late collisions

  0 lost carrier, - no carrier

So, what would you recommend:

a) Put in an optics with more "power" on one site?

b) Change the passive multiplexer with less insertion loss. Vendor Pan Dacom says for its "SPEED-CWDM-81E:" (MUX + DEMUX) is max: 3,85 dB What passive multiplexer would you reommend?

For a) I would need optics with higher costs for all channels. So I´ll try b) What is your opinion?

Update: I am asking myself whether that single optic from FS is actually bad...