@elizar said in Weird issue when pinging an external server: @shedaim Ping'ing takes time. Maybe the successful reply to the second ping is in fact the answer to the first ping? Using the newly added "delay" option should have fixed that, so I don't believe that's what's happening. This is what I managed to find out untill now: Trying a single ping message: Ping request UE --> Server Success Ping reply Server --> EPG Success Ping reply EPG --> MME Success Ping reply MME --> eNodeB Success Ping reply eNodeB --> UE Unknown (Doesn't show in Atom, but MME states that message has been sent) Trying two pings in rapid succession: Ping request UE --> Server Success Ping reply Server --> EPG Success Ping reply EPG --> MME Success Ping reply MME --> eNodeB Success ping reply eNodeB --> UE Unknown (Doesn't show in Atom, but MME states that message has been sent) Ping request UE --> Server Success ping reply Server --> UE Success (Arrives after 150 - 500 ms) Pinging from server to UE is successful continuously. eDRX is in state "NOT_CONFIGURED" - same as network. Tried to disable sleep of the modem using AT!="EE::disable" Additional information for the Pros: First Ping message is sent over S1AP/NAS-EPS in the initial message to the MME, which contains a Control Plane Service Request. Second ping message is sent over the same interface as an UplinkNasTransport message. Wireshark of MME messages - Download