Describe the bug
A clear and concise description of what the bug is.

To Reproduce
Steps to reproduce the behavior:

1. lotus-miner run
2. See error
   

Expected behavior

Miner was running normally
ip and port have not changed.
But suddenly the miner stops and the synchronization fails
After re-synchronization, when Minor is executed, the error is continuously displayed.
Port forwarding setting IP port All connections are completed and there is no problem.

Screenshots
If applicable, add screenshots to help explain your problem.

Version (run lotus version):

lotus version 0.8.0+git.2c1d96bc