勞請網路界先進解惑(上網速率不足問題)

小弟申請一路 TFN 光纖網路，速率(5M/20M)，近日發覺速率變得奇怪，上傳大於下載(上傳4.89M無誤，下載僅有2~3M)，昨日通報台固客服&中華(0800080128)報修。報修今日華信即派工到府維修，工程師稱數據機軔体過久所致(P-874)，故將數據機軔体更新，更新完後當下測試確實速率恢復正常(4.9M/19.6M)，然而當工程師離開後沒多久，又變成不正常速率(上傳4.97M，下載僅1.79M)，試問先進，該問題可能發生端點究竟是華信端或台固端，望請告知，以利小弟追查故障原因？

感謝！

以下為數據機參數

============================================================================
VDSL Training Status: Showtime
VDSL Profile: Profile 17a
Traffic Type: PTM Mode
============================================================================
VDSL Port Details Upstream Downstream
Line Rate: 5.419 Mbps 21.643 Mbps
Actual Net Data Rate: 5.375 Mbps 21.567 Mbps
Trellis Coding: ON ON
SNR Margin: 31.6 dB 21.1 dB
Actual Delay: 5 ms 7 ms
Transmit Power: -13.6 dBm -10.0 dBm
Receive Power: -23.3 dBm -18.8 dBm
Actual INP: 17.0 symbols 26.0 symbols
Total Attenuation: 9.4 dB 8.8 dB
Attainable Net Data Rate: 55.330 Mbps 112.940 Mbps
============================================================================
VDSL Band Status U0 U1 U2 U3 D1 D2 D3
Line Attenuation(dB): 0 .8 8 .2 11.1 N/A 4 .9 10.9 17.2
Signal Attenuation(dB): 0 .8 7 .5 10.6 N/A 4 .9 10.9 17.2
SNR Margin(dB): 33.5 31.5 31.5 N/A 20.9 20.9 21.2
Transmit Power(dBm):-30.3 -23.6 -14.5 N/A -15.1 -15.6 -13.8
============================================================================

Since Link time = 12 min 29 sec
FEC: 2 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Latest 15 minutes time = 12 min 51 sec
FEC: 2 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 22 22
LOS: 0 0
LOF: 0 0
LOM: 0 0
Previous 15 minutes time = 0 sec
FEC: 0 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Latest 1 day time = 12 min 51 sec
FEC: 2 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 22 22
LOS: 0 0
LOF: 0 0
LOM: 0 0
Previous 1 day time = 0 sec
FEC: 0 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
LOM: 0 0
Total time = 13 min 6 sec
FEC: 2 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 22 22
LOS: 0 0
LOF: 0 0
LOM: 0 0

============================================================================