ERROR LOG: DCB_STATE_POLLING failed: 104, Connection reset by peer

After we upgraded our Apache version on web server to 2.4.46
I've got some error messages in Maxscale log file.
Could you tell me what the message means ?
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2020-10-21 18:39:11 error : (4236060) Write to Client DCB 192.168.0.21 in state DCB_STATE_POLLING failed: 104, Connection reset by peer
2020-10-21 18:41:16 error : (4236523) Write to Client DCB 192.168.0.21 in state DCB_STATE_POLLING failed: 104, Connection reset by peer
2020-10-21 18:41:22 error : (4236559) Write to Client DCB 192.168.0.21 in state DCB_STATE_POLLING failed: 104, Connection reset by peer
2020-10-21 18:41:51 error : (4236672) Write to Client DCB 192.168.0.21 in state DCB_STATE_POLLING failed: 104, Connection reset by peer
2020-10-21 18:42:08 error : (4236740) Write to Client DCB 192.168.0.21 in state DCB_STATE_POLLING failed: 104, Connection reset by peer
2020-10-21 18:42:54 error : (4236908) Write to Client DCB 192.168.0.21 in state DCB_STATE_POLLING failed: 104, Connection reset by peer
2020-10-21 18:43:02 error : (4236939) Write to Client DCB 192.168.0.21 in state DCB_STATE_POLLING failed: 104, Connection reset by peer
2020-10-21 18:44:29 error : (4237246) Write to Client DCB 192.168.0.23 in state DCB_STATE_POLLING failed: 104, Connection reset by peer
2020-10-21 18:46:13 error : (4237631) Write to Client DCB 192.168.0.23 in state DCB_STATE_POLLING failed: 104, Connection reset by peer
2020-10-21 18:49:49 error : (4238337) Write to Client DCB 192.168.0.23 in state DCB_STATE_POLLING failed: 104, Connection reset by peer
2020-10-21 18:50:52 error : (4238561) Write to Client DCB 192.168.0.23 in state DCB_STATE_POLLING failed: 104, Connection reset by peer
2020-10-21 18:51:19 error : (4238669) Write to Client DCB 192.168.0.21 in state DCB_STATE_POLLING failed: 104, Connection reset by peer
2020-10-21 18:51:31 error : (4238704) Write to Client DCB 192.168.0.21 in state DCB_STATE_POLLING failed: 104, Connection reset by peer
2020-10-21 18:51:49 error : (4238747) Write to Client DCB 192.168.0.21 in state DCB_STATE_POLLING failed: 104, Connection reset by peer
2020-10-21 18:54:13 error : (4239168) Write to Client DCB 192.168.0.21 in state DCB_STATE_POLLING failed: 104, Connection reset by peer
2020-10-21 18:55:32 error : (4239427) Write to Client DCB 192.168.0.21 in state DCB_STATE_POLLING failed: 104, Connection reset by peer
2020-10-21 18:56:14 error : (4239583) Write to Client DCB 192.168.0.21 in state DCB_STATE_POLLING failed: 104, Connection reset by peer
2020-10-21 18:56:22 error : (4239624) Write to Client DCB 192.168.0.21 in state DCB_STATE_POLLING failed: 104, Connection reset by peer
2020-10-21 18:57:03 error : (4239761) Write to Client DCB 192.168.0.23 in state DCB_STATE_POLLING failed: 104, Connection reset by peer
2020-10-21 18:58:30 error : (4240004) Write to Client DCB 192.168.0.23 in state DCB_STATE_POLLING failed: 104, Connection reset by peer
2020-10-21 18:58:57 error : (4240085) Write to Client DCB 192.168.0.23 in state DCB_STATE_POLLING failed: 104, Connection reset by peer
2020-10-21 18:59:51 error : (4240266) Write to Client DCB 192.168.0.23 in state DCB_STATE_POLLING failed: 104, Connection reset by peer
2020-10-21 19:00:25 error : (4240384) Write to Client DCB 192.168.0.23 in state DCB_STATE_POLLING failed: 104, Connection reset by peer
2020-10-21 19:01:34 error : (4240623) Write to Client DCB 192.168.0.23 in state DCB_STATE_POLLING failed: 104, Connection reset by peer
2020-10-21 19:01:57 error : (4240703) Write to Client DCB 192.168.0.23 in state DCB_STATE_POLLING failed: 104, Connection reset by peer
2020-10-21 19:02:43 error : (4240829) Write to Client DCB 192.168.0.23 in state DCB_STATE_POLLING failed: 104, Connection reset by peer
2020-10-21 19:03:24 error : (4240954) Write to Client DCB 192.168.0.23 in state DCB_STATE_POLLING failed: 104, Connection reset by peer
2020-10-21 19:03:57 error : (4241052) Write to Client DCB 192.168.0.23 in state DCB_STATE_POLLING failed: 104, Connection reset by peer
2020-10-21 19:04:51 error : (4241238) Write to Client DCB 192.168.0.23 in state DCB_STATE_POLLING failed: 104, Connection reset by peer
2020-10-21 19:04:55 error : (4241246) Write to Client DCB 192.168.0.23 in state DCB_STATE_POLLING failed: 104, Connection reset by peer
2020-10-21 19:05:05 error : (4241294) Write to Client DCB 192.168.0.23 in state DCB_STATE_POLLING failed: 104, Connection reset by peer