What device are you connecting to. 8 usually means that if peer is a slave it stops answering polls, or if peer is a master the peer stopped polling our device. For example if peer is a phone and phone is turned off (or enters airplane mode), you will see that. If you think peer is not being turned off, you may want to check connection interval/link supervision timeout setup for your link. For example if connection interval is half a second and link supervision timeout is 1 second if you miss two polls due to the interference the connection will go down with result code 8. If you are a peripheral make sure that you call bleprofile_SendConnParamUpdateReq after connection is established. Try to increase the last parameter (supervision timeout) and see if it helps. Check hello_sensor for details. If you are the central try to increase blecen_cen_cfg.high_supervision_timeout and blecen_cen_cfg.low_supervision_timeout.
