sv_port 0
sv_external_port 0

Why are you trying to run a server on that port? Choose a standard Teeworlds port as Pikotee said,
like 8303, and it'll work fine..probably. I'm running a server on port 1337 and people are able to follow me onto it, but I can't find it in the server list half of the time.
Just so map switching should work better, might wanna remove ".cfg" from the map names. Just leave them as .map files and it'll all be fine

Good luck!

but the thing is that it says "failed to open 'data/maps/dm1cfg'"

It would seem to me that you have saves of maps that have the extension .cfg, which makes no sense at all. They have to have the extension .map. Though correct me, if that is supposed to be like that. I highly doubt it though.

I believe you are missing the sv_map line there, although that shouldn't be a big problem as the server is going to load the default map anyways.

The firewall is really not getting in your way here, you can have it turned on all the time, as far as I know.

In the end I want to ask if we are actually talking about a LAN server or a public one. Because I cannot help you with the second topic.

Best regards,

TheDerero.

teeworlds_srv -f autoexec.cfg is not needed if the config's name is autoexec.cfg, just double click on the .exe.

if you do sv_port 8303 (or any other between 8300 and 8310) the server will appear in LAN-tab, but other player will be able to join aswell.

if you choose another port, like sv_port 1111 you should find the server in Internet-Tab

Greetings Piko

I'm not sure (someone correct me if I'm wrong) but you cant see your own server on the Internet list if you're running it on the same network as you are.
Ask someone else if he can finds the server on the server list and try to find it yourself on the Lan Tab.

If the person can't, give him the IP address for a direct connection.

Btw, are you connected to your router via cable or WLAN?

although, it says
server registered
it doesn't show up in a game search. (I tried changing up the filter)

but the thing is that it says "failed to open 'data/maps/dm1cfg'"
and "failed to open 'failed to open 'data/maps/dm1.maps.cfg'"

I "think" this is the problem.

I saved  autoexec.cfg liked this,

sv_name Cittttty
sv_port 0
sv_external_port 0
sv_max_clients 12
sv_max_clients_per_ip 2
sv_register 1
sv_rcon_password admin
console_output_level 0
sv_rcon_max_tries 3
sv_rcon_bantime 5

-------------------------------

and i ran it using .bat file

teeworlds_srv -f autoexec.cfg

Please help thank you

oh by the way, i did disable the firewall
because it said 
"no firewall/nat problems detected"
"no firewall/nat problems detected"