ZTE F7015T optical cat plugs into 2 ports at the same time, how to solve the frequent drop of packets on the network?

friend just replaced the ZTE F7015T optical cat today, plugging into any network port (2.5G port and Gigabit port) network is normal, but only two of the network ports are plugged in, the network frequently drops packets, web pages cannot be opened or opened slowly, and WeChat messages are slow to send and receive. It's no problem to look at the settings in the background of the light cat. Please help me see what is wrong and how to set it up? Or is there something wrong with the light cat?

1. first do 3 30-second quick verification 1.1 only plug in the 2.5G port + a PC, and run ping -t 119.29.29.29 for 3 minutes to see if there is packet loss.
   1.2 Repeat the same test with only the Gigabit port plugged in.
   1.3 Plug in both ports at the same time, but turn off the PC of one of them immediately (the network port light is still on), and then run ping.

• If you don't lose 1 and 2, 3 starts to lose → The problem appears instantly when you "power on both mouths at the same time", continue to step 2.
• if 1 or 2 are lost alone → There is a problem with the light cat itself or the outside line, skip step 3 directly.

2. software/configuration layer (0 cost, 5 minutes)
   2.1 Turn off "dual-port binding/port aggregation"
   use the super password to enter the background (telecomadmin / nE7jA%5m or the new password given to you) → network → Port binding → Remove all the checkmarks in front of "port aggregation/LACP", save and restart.
   F7015T early firmware defaults to 2.5G+LAN1 as trunk, and in home scenarios, as long as it is enabled, STP packets will be sent wildly, which will directly cause packet drops.

3. hardware/line layer
   3.1 Receive power check
   enter the background "status→PON information" to see the light, -8 ~ -25 dBm is considered normal; If the two ports jump below -27 dBm as soon as they are plugged in, it means that the optical transceiver/splitter port is loose, call the operator and ask the installation tape dust-free paper to re-wipe the APC head and replace the splitter.

• first replace two confirmed short-term wires (within 1 m) and then test;
• log in to the background "Status→LAN port information" to observe whether the 2.5G port occasionally drops from 2500 M to 1000 M or even 100 M, if there is a poor physical contact of the → port, it is a hardware defect.
• if you only need to plug in the second port, the first port rate will drop, and it can be determined that the optical cat motherboard switch chip is falsely soldered, and the whole machine can only be replaced.

4. temporary avoidance plan (it really can't be solved first)

• use the 2.5G port as the main port, the other port is empty, and then connect to a 2.5G switch and then split the line to bypass the optical cat's internal exchange chip.
• allows operators to bridge the F7015T and hang their own 2.5G router dialing behind.