Find what you see.

Please start with the FAQ questions below: most trouble is one of these. Each has the same label on every page, Q1 to Q10. Then the problems we know for this step, each with its cause and fix.

1. Q3

   Is a headset plugged into each PC, and the one microphone into the host PC?

   How to tell: With no microphone, the host's Microphone picker reads "No microphone found. Plug one in to host." With no headset or speakers, the Headset picker reads "No headset or speakers found. Plug one in." The host PC needs a headset too: it plays the microphone in its own headset, and without one Host stops with the red banner "Could not open the output device: … (is a headset or speakers plugged in and turned on?)" The lists are read when the app opens and again after every Leave.

   What to do: Please plug the device in, then close and reopen the app, or press Leave once. If the host links but an amber line reads "The mic is sending pure silence. In Settings › Privacy & security › Microphone, let desktop apps use the microphone.", turn that setting on. The joining PC needs no microphone. If the voice feels late, please try a wired headset: a wireless one adds its own delay.

   On CO-OP Comms Client Only: Client Only needs no microphone, only a headset or speakers. With none, its Headset picker reads "No headset or speakers found. Plug one in."

   

   

   

   

2. Q6

   Are both PCs on the same subnet, and able to reach each other?

   How to tell: CO-OP Comms is made for two PCs on the same subnet of one local network. The list of hosts stays on the local network: it reaches every PC on the same subnet (PCs plugged into the same router or switch), it never goes out to the WAN (the internet), and it does not pass between two separate subnets in one building. Compare the two addresses: each PC shows its own under This PC on its start screen. On most home and office networks, PCs on one subnet have addresses whose first three numbers match, such as 192.168.1.160 and 192.168.1.21; 192.168.1.160 and 192.168.5.40 are on different subnets. Matching numbers are not proof. Guest Wi-Fi, Wi-Fi that keeps devices apart ("AP isolation" or "client isolation"), separate VLANs, a DMZ, or a test lab that isolates each machine look the same in the numbers and still keep the PCs apart. The signs are in the windows: the host is hosting, but the joining PC's list stays empty after 10 seconds, and a typed address gets "No answer from …" after 8 seconds. On Wi-Fi, once linked, a grey line reads "This PC is on Wi-Fi. CO-OP Comms is made for wired Ethernet; over Wi-Fi, expect more delay and gaps in the sound."

   What to do: Please plug both PCs into the same router or switch with a cable, on the main network, not a guest network. On a managed or test network, please ask your IT staff: "These two PCs need to reach each other directly on one local network: the same subnet, with no client isolation or firewall between them, and UDP ports 47800 and 47801 allowed both ways. Can you please put them there?" The rule: the list finds hosts on the same subnet only; typing the host PC's address is tried for any address, private or public, on another subnet too. It links when the network between the PCs lets UDP port 47800 through both ways; machines kept apart still will not connect. We test one subnet, and have not yet tried a typed join across a router.

   On CO-OP Comms Client Only: Client Only has no "This PC" line. Its own address shows in the Network picker, such as "Ethernet · 192.168.1.21". Read the host's address from the host's "This PC" line.

3. Q5

   Is either PC reached by remote desktop, a cloud PC or a VPN?

   How to tell: The network is where the PC is, not where you are. Over remote desktop the app runs on the far PC, on its network, and its sound goes through the remote-desktop program's "Remote Audio" devices. The list of hosts does not reach a PC over a VPN, and many cloud networks do not pass it either.

   What to do: Please sit at both PCs, on the same subnet of one home or office network: no online service, made for the local network only. We have not tested it over remote desktop, a cloud PC or a VPN.

4. Q4

   Is either PC a virtual machine?

   How to tell: The app cannot tell that it runs in a VM. A VM on NAT, the default in most VM software, sits behind its own host PC's address on a subnet of its own: the host list cannot see across it, and nothing outside can reach it to join. A VM's sound comes from its virtual sound card.

   What to do: Please use two real PCs on one router or switch. If a VM must be used, set its network to bridged, so it gets an address on the same subnet as the other PC (Q6), and check that its Headset and Microphone pickers list real devices. We have not tested CO-OP Comms in a VM.

Problems we know for step 3A

1. 3A-1

   JOINED, but nothing is heard.

   Why

   The host's Mute is on, its microphone is silent (Q3), the noise gate is set too high, the joining PC's own Mute is on, or it plays to the wrong headset.

   Fix

   On the host PC: check that Mute is OFF and that the MIC meter moves; speak up, or press − on the noise gate. On the joining PC: check that its own Mute is OFF; if it is, press Leave, pick the headset, and Join again.

   On CO-OP Comms Client Only: On Client Only, its own Mute silences this PC's headset, and the level bar drops to nothing (client-guest-muted.png). Please turn it off again.

   

   

   Show it in CO-OP Comms Client Only

2. 3A-2

   I see This PC is on Wi-Fi. CO-OP Comms is made for wired Ethernet; over Wi-Fi, expect more delay and gaps in the sound.

   A grey line once linked, or the sound comes in gaps or late.

   Why

   Wi-Fi (Q6), remote desktop sound (Q5), or a VM (Q4).

   Fix

   Please plug both PCs into the router or switch with a cable, sit at the PCs themselves, and use real PCs, not VMs.

   

   

3. 3A-3

   I see The microphone stopped. Check that it is plugged in, then press Host again.

   A red banner on the host PC's start screen; on the joining PC, "The headset stopped. Check that it is plugged in, then press Join again."

   Why

   The microphone or headset was unplugged, or its driver reset, and it did not come back within 2 seconds. The link ends; nothing restarts it by itself.

   Fix

   Please plug it back in, check that it is picked, then press Host (or Join) again.