Look at each line in the ethtool output below that includes the word "threshold". This file shows the actual output from ethtool v4.18, when the output is not piped to another command. Notice that all of the displayed threshold values are 0 (which is incorrect), while other values report as expected. tech1@D8:~$ sudo ethtool -m enp1s0 Identifier : 0x11 (QSFP28) Extended identifier : 0xfc Extended identifier description : 3.5W max. Power consumption Extended identifier description : CDR present in TX, CDR present in RX Extended identifier description : High Power Class (> 3.5 W) not enabled Connector : 0x07 (LC) Transceiver codes : 0x80 0x00 0x00 0x00 0x00 0x00 0x00 0x00 Transceiver type : 100G Ethernet: 100G CWDM4 MSA with FEC Encoding : 0x03 (NRZ) BR, Nominal : 25500Mbps Rate identifier : 0x00 Length (SMF,km) : 2km Length (OM3 50um) : 0m Length (OM2 50um) : 0m Length (OM1 62.5um) : 0m Length (Copper or Active cable) : 0m Transmitter technology : 0x40 (1310 nm DFB) Laser wavelength : 1310.000nm Laser wavelength tolerance : 47.500nm Vendor name : TRANSITION Vendor OUI : 00:c0:f2 Vendor PN : TNQSFP100GCWDM4 Vendor rev : 1A Vendor SN : TN02000302 Date code : 180919 Revision Compliance : SFF-8636 Rev 2.5/2.6/2.7 Module temperature : 39.53 degrees C / 103.15 degrees F Module voltage : 3.3241 V Alarm/warning flags implemented : Yes Laser tx bias current (Channel 1) : 34.432 mA Laser tx bias current (Channel 2) : 34.432 mA Laser tx bias current (Channel 3) : 33.408 mA Laser tx bias current (Channel 4) : 33.920 mA Transmit avg optical power (Channel 1) : 0.9048 mW / -0.43 dBm Transmit avg optical power (Channel 2) : 0.7832 mW / -1.06 dBm Transmit avg optical power (Channel 3) : 0.8057 mW / -0.94 dBm Transmit avg optical power (Channel 4) : 0.7014 mW / -1.54 dBm Rcvr signal avg optical power(Channel 1) : 0.7378 mW / -1.32 dBm Rcvr signal avg optical power(Channel 2) : 0.7553 mW / -1.22 dBm Rcvr signal avg optical power(Channel 3) : 0.6529 mW / -1.85 dBm Rcvr signal avg optical power(Channel 4) : 0.6847 mW / -1.64 dBm Laser bias current high alarm (Chan 1) : Off Laser bias current low alarm (Chan 1) : Off Laser bias current high warning (Chan 1) : Off Laser bias current low warning (Chan 1) : Off Laser bias current high alarm (Chan 2) : Off Laser bias current low alarm (Chan 2) : Off Laser bias current high warning (Chan 2) : Off Laser bias current low warning (Chan 2) : Off Laser bias current high alarm (Chan 3) : Off Laser bias current low alarm (Chan 3) : Off Laser bias current high warning (Chan 3) : Off Laser bias current low warning (Chan 3) : Off Laser bias current high alarm (Chan 4) : Off Laser bias current low alarm (Chan 4) : Off Laser bias current high warning (Chan 4) : Off Laser bias current low warning (Chan 4) : Off Module temperature high alarm : Off Module temperature low alarm : Off Module temperature high warning : Off Module temperature low warning : Off Module voltage high alarm : Off Module voltage low alarm : Off Module voltage high warning : Off Module voltage low warning : Off Laser tx power high alarm (Channel 1) : Off Laser tx power low alarm (Channel 1) : Off Laser tx power high warning (Channel 1) : Off Laser tx power low warning (Channel 1) : Off Laser tx power high alarm (Channel 2) : Off Laser tx power low alarm (Channel 2) : Off Laser tx power high warning (Channel 2) : Off Laser tx power low warning (Channel 2) : Off Laser tx power high alarm (Channel 3) : Off Laser tx power low alarm (Channel 3) : Off Laser tx power high warning (Channel 3) : Off Laser tx power low warning (Channel 3) : Off Laser tx power high alarm (Channel 4) : Off Laser tx power low alarm (Channel 4) : Off Laser tx power high warning (Channel 4) : Off Laser tx power low warning (Channel 4) : Off Laser rx power high alarm (Channel 1) : Off Laser rx power low alarm (Channel 1) : Off Laser rx power high warning (Channel 1) : Off Laser rx power low warning (Channel 1) : Off Laser rx power high alarm (Channel 2) : Off Laser rx power low alarm (Channel 2) : Off Laser rx power high warning (Channel 2) : Off Laser rx power low warning (Channel 2) : Off Laser rx power high alarm (Channel 3) : Off Laser rx power low alarm (Channel 3) : Off Laser rx power high warning (Channel 3) : Off Laser rx power low warning (Channel 3) : Off Laser rx power high alarm (Channel 4) : Off Laser rx power low alarm (Channel 4) : Off Laser rx power high warning (Channel 4) : Off Laser rx power low warning (Channel 4) : Off Laser bias current high alarm threshold : 0.000 mA Laser bias current low alarm threshold : 0.000 mA Laser bias current high warning threshold : 0.000 mA Laser bias current low warning threshold : 0.000 mA Laser output power high alarm threshold : 0.0000 mW / -inf dBm Laser output power low alarm threshold : 0.0000 mW / -inf dBm Laser output power high warning threshold : 0.0000 mW / -inf dBm Laser output power low warning threshold : 0.0000 mW / -inf dBm Module temperature high alarm threshold : 0.00 degrees C / 32.00 degrees F Module temperature low alarm threshold : 0.00 degrees C / 32.00 degrees F Module temperature high warning threshold : 0.00 degrees C / 32.00 degrees F Module temperature low warning threshold : 0.00 degrees C / 32.00 degrees F Module voltage high alarm threshold : 0.0000 V Module voltage low alarm threshold : 0.0000 V Module voltage high warning threshold : 0.0000 V Module voltage low warning threshold : 0.0000 V Laser rx power high alarm threshold : 0.0000 mW / -inf dBm Laser rx power low alarm threshold : 0.0000 mW / -inf dBm Laser rx power high warning threshold : 0.0000 mW / -inf dBm Laser rx power low warning threshold : 0.0000 mW / -inf dBm