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.

This step needs CO-OP Comms. It cannot be done in CO-OP Comms Client Only. Show this page for CO-OP Comms

1. Q7

   Was the Windows firewall prompt answered Deny, or closed without an answer?

   How to tell: Either one adds Block rules for the program, and a Block rule wins over every Allow rule, Steam's included. The host then hears no joins: the joining PC shows "No answer from …" after 8 seconds, and the host stays on "No guest yet".

   What to do: Please open Windows Security › Firewall & network protection › Advanced settings › Inbound Rules. Delete the Block rules naming roomMicApp.exe. Start CO-OP Comms, press Host, and answer the prompt Allow with Private networks ticked. If the network is set to Public, set it to Private in Settings › Network & internet › Ethernet (or Wi-Fi) › Network profile type, or allow the app on Public too.

   On CO-OP Comms Client Only: On the Client Only PC, please delete the Block rules that name roomMicClient.exe. Client Only receives the sound on UDP 47800 and the host list on UDP 47801, so a Block rule there stops both.

2. Q8

   Is a second copy already running on this PC?

   How to tell: Pressing Host or Join shows the red banner "UDP port 47800 is in use by another program, perhaps a second copy of CO-OP Comms, and two copies cannot share it on one PC. Close the other one, then try again." CO-OP Comms and Client Only count as two copies.

   What to do: Close the other copy; look in Task Manager for roomMicApp.exe. Each PC runs one copy, and one PC cannot be both host and joiner, so this test needs two PCs.

   On CO-OP Comms Client Only: In Task Manager, please look for roomMicClient.exe as well as roomMicApp.exe.

   

   

3. 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.

4. Q1

   Was it installed through Steam, or run from a copied folder?

   How to tell: The top-right corner shows this PC's Steam user name only when Steam started the app. A copy started any other way reads "Steam not running", even with Steam open.

   What to do: Please install and start it from the Steam library on both PCs. Only the names change without Steam; the real difference is the firewall. Steam's install adds an allow rule named "CO-OP Comms" for the program in the Steam folder, and a copy run from another folder gets the Windows Security Alert the first time it hosts or listens (Q7).

   On CO-OP Comms Client Only: On Client Only the corner shows the Steam name only when Steam started it; otherwise it reads "Steam not running". Its Windows prompt names it "CO-OP Comms Client Only".

Problems we know for step 1C

1. 1C-1

   I see UDP port 47800 is in use by another program, perhaps a second copy of CO-OP Comms, and two copies cannot share it on one PC. Close the other one, then try again.

   A red banner, when Host is pressed.

   Why

   A second copy is running on this PC (Q8).

   Fix

   Close the other copy, then press Host again.

   

2. 1C-2

   I see Could not open the input device: …

   A red banner, when Host is pressed. The words after it come from Windows.

   Why

   Another program holds the microphone (Q3).

   Fix

   Close that program, or pick another microphone, then press Host again.

   

3. 1C-3

   A Windows Security Alert asks whether to allow CO-OP Comms on networks.

   Why

   Windows asks the first time a program listens on the network, when it has no allow rule (Q1).

   Fix

   Answer Allow, with Private networks ticked. If it was answered Deny or closed, see Q7.

4. 1C-4

   I see This PC has no network connection. Connect it to the same router or switch as the other PC, then press Leave and Host again.

   An amber line while hosting.

   Why

   This PC has no network connection.

   Fix

   Please connect it to the same router or switch as the other PC, then press Leave and Host again.

   

5. 1C-5

   I see On the other PC, pick "host's Steam user name" from the list, or type host PC's address and press Join. Still nothing? Check that the two PCs can reach each other, and that Windows Security › Firewall & network protection allows CO-OP Comms.

   Words shaded like this stand for what your own screen shows there, such as your own user name or address.

   The host PC stays on HOSTING, "Waiting for the other PC" and "No guest yet"; after 20 seconds the line gains its second sentence.

   Why

   No join has reached this PC. Most likely the two PCs are not on one subnet, or the network keeps them apart, as test machines in a DMZ, on separate VLANs or in an isolated lab are (Q6); or this PC's firewall blocks the join (Q7). Or the joining PC never pressed Join, or typed a wrong address; its own screen then says which (2C-1, 2D-1, 2D-2).

   Fix

   Look at the joining PC's screen first. Then compare the two PCs' addresses and, on a managed network, please ask your IT staff whether they can reach each other (Q6). Then go through Q7 on this PC.

   

6. 1C-6

   I see Could not open the output device: … (is a headset or speakers plugged in and turned on?)

   A red banner, when Host is pressed. The words after the colon come from Windows.

   Why

   The host PC has no headset or speakers to play to, or another program holds them. The host plays the microphone in its own headset, so it needs one as much as the joining PC does (Q3).

   Fix

   Please plug a headset into the host PC, pick it in the Headset picker, and press Host again.