It was always "Looking for peers"

[zangjiahe]

0|geth-mainet  | INFO [09-08|14:57:31.296] Looking for peers                        peercount=0 tried=29 static=0
0|geth-mainet  | INFO [09-08|14:57:41.415] Looking for peers                        peercount=0 tried=19 static=0
0|geth-mainet  | INFO [09-08|14:57:51.415] Looking for peers                        peercount=0 tried=22 static=0
0|geth-mainet  | INFO [09-08|14:58:01.415] Looking for peers                        peercount=0 tried=33 static=0
0|geth-mainet  | INFO [09-08|14:58:11.435] Looking for peers                        peercount=1 tried=30 static=0
0|geth-mainet  | INFO [09-08|14:58:21.539] Looking for peers                        peercount=0 tried=38 static=0
0|geth-mainet  | INFO [09-08|14:58:31.748] Looking for peers                        peercount=0 tried=30 static=0
0|geth-mainet  | ERROR[09-08|14:58:32.154] Snapshot extension registration failed   peer=ba83bd0f err="peer connected on snap without compatible eth support"
0|geth-mainet  | INFO [09-08|14:58:41.807] Looking for peers                        peercount=0 tried=29 static=0
0|geth-mainet  | INFO [09-08|14:58:51.878] Looking for peers                        peercount=0 tried=36 static=0
0|geth-mainet  | ERROR[09-08|14:58:55.873] Snapshot extension registration failed   peer=db3b65b7 err="peer connected on snap without compatible eth support"
0|geth-mainet  | ERROR[09-08|14:59:00.473] Snapshot extension registration failed   peer=089e2e46 err="peer connected on snap without compatible eth support"
0|geth-mainet  | ERROR[09-08|14:59:01.837] Snapshot extension registration failed   peer=b504b033 err="peer connected on snap without compatible eth support"
0|geth-mainet  | INFO [09-08|14:59:02.081] Looking for peers                        peercount=0 tried=32 static=0
0|geth-mainet  | ERROR[09-08|14:59:08.093] Snapshot extension registration failed   peer=04dfa983 err="peer connected on snap without compatible eth support"
0|geth-mainet  | INFO [09-08|14:59:12.082] Looking for peers                        peercount=1 tried=39 static=0
0|geth-mainet  | INFO [09-08|14:59:22.082] Looking for peers                        peercount=2 tried=30 static=0

Above is the log that caused the problem, often in this state and not working, unable to produce mining jobs
Firewalls on ports 8545 and 30303 have been opened, including TCP and UDP

[ziogaschr]

1. On which version of core-geth are you running?
2. What operating system?
3. Which network? classic, mordor, kotti?
4. Can you share you core-geth startup command?