Internet connection not working when I open my desktop

I have a 2 modem, 1) Is where the main connection is, 2) Is just a wifi which gets a connection from modem 1).
My desktop has a wired router onto modem 1.

The problem is when I try to open my modem 1 & 2, it has internet connections. But when i try to open my desktop while the 2 modems are on, the internet connection isnt working.

Only the way it works is when the 2 modems are on while the desktop is shut down.
Or the desktop & modem 1 are open but modem 2 isnt turned on.

How can i fix this problem? Need help ASAP.

I am a bit confused. So, will ask a few questions to clarify:
- When you say a modem - do you mean Network Connection? Look at the screenshot

- Or do you mean (1) is modem/router and (2) is wireless access point?

It is possible that your wireless is getting disconnected when a wired connection is present. But all speculation on my end because frankly we have a language barrier at the moment.

My pc is connected to the local area connection, and dont have wireless network connection. The wireless is just for our cellphones.

At first the 2 modems are working, but when i try to open now my desktop, the internet connection disappears but at the modem 1, its blinking "green".

It is possible that your 1st modem is in "bridge mode". When PC is off, wireless router gets the IP and works, but gives the IP to your computer once you turn it on.

Can you describe the 1st modem? How many LAN(Ethernet) ports are there at the back?

Does your wireless have any LAN ports? Describe its back side too.

Perhaps take photographs of the back sides, and post here.

Right modem 1, left modem 2(wifi).
The ports that have color yellow frames are the LAN ports. And the silver router is on LAN port modem 1 connected on WAN port on modem 2.

Do you have 3 different computers? All yellow cables go to a different computer? If any yellow cable go from modem 1 to modem 2 then remove it. Only cable between modem 1 (LAN port) and modem 2 (WAN port) should be the grey one. PC can connect to any yellow LAN port on either modem 1 or modem 2.

Let us know how it goes after you remove that extra yellow cable between modem 1 and 2.

(By the way, it is 3:22AM here, so I am going to bed and won't be able to answer. Hopefully, this will solve your problem. If not, check modem 1 management interface to see if it is in bridged mode, and disable bridged mode if so. It should be doing NAT.)

Okay go get some sleep bro, thanks for the suggestions. Ill try that.
Its the DHCP right? So ill try to disable it

GokAy said:

Do you have 3 different computers? All yellow cables go to a different computer? If any yellow cable go from modem 1 to modem 2 then remove it. Only cable between modem 1 (LAN port) and modem 2 (WAN port) should be the grey one. PC can connect to any yellow LAN port on either modem 1 or modem 2.

Let us know how it goes after you remove that extra yellow cable between modem 1 and 2.

(By the way, it is 3:22AM here, so I am going to bed and won't be able to answer. Hopefully, this will solve your problem. If not, check modem 1 management interface to see if it is in bridged mode, and disable bridged mode if so. It should be doing NAT.)

I removed the yellow cable that connects modem 1 to 2 and its working now :).
Thank you so much guys for your suggestions.

But why last week it was just working with a yellow cable like that? Does the DHCP enabled makes the conflict?

Yes, you can connect yellow the cable from modem 1 LAN to modem 2 LAN (remove grey cable in that case). But make sure to disable one of the DHCP's. Two DHCP simultaneously will cause problems.