Internet connectivity issues after adding second NIC

[shelms488]

Okay, I am at a loss for what to do here. I am not even really sure what to do to go about diagnosing this issue. here is my setup:
50Mbps cable internet come into Motorola SB6141.
Modem connects to Asus RT-AC87U via Cat 7 S/STP 3 foot cable.
Router connects to various devices.
Router connects to TRENDnet TEG-S80g 1 Gbps switch
Switch connects to PC and other devices including Synology DS1815+ via cat 7 S/STP cables (under 10 feet.)
Computer NIC to switch is Intel I218-V on a ASUS Sabertooth X99 motherboard.
Computer has a static network configuration on the Intel NIC as follows:
IP Address: 192.168.174.xx
Subnet Mask: 255.255.255.0
Default Gateway: 192.168.174.xz
Synology DS1815+ also has a static network configuration as follows:
IP Address: 192.168.174.xy
Subnet Mask: 255.255.255.0
Default Gateway: 192.168.174.xz.
The computer is also connected directly to Synology DS1815+ with a Cat 6a crossover cable on a
Realtek PCIe GBE Family Controller that is also a static configuration as follows
PC:
IP Address: 169.254.141.1xx
Subnet Mask: 255.255.0.0
Default Gateway: None
Jumbo frames on: 9000 bytes
Synology DS1815+
IP Address: 169.254.141.1xy
Subnet Mask: 255.255.0.0
Default Gateway: None
Jumbo Frames on: 9000 bytes

PC uses Google Chrome browser but issue also occurs with Firefox.
Hopefully, I have described the network adequately enough.

Now the problem started when I connected the DS1815+ via the crossover cable to the PC. before that no issues had occurred. through the local network, especially the direct connection to the NAS I am getting +/- 115 MBps transfer speeds which is close to the maximum capable throughput, which I love. The issue is when I attempt to connect to almost any website, doesn't matter what it is, or if I return to the a tab after a period of inactivity and refresh it. I usually receive a connection timeout error on the first try and this is corrected by a refresh of the page. This is quite annoying. I still seem to be receiving my full connection speed, but something is going on with the latency. Hopefully someone smarter than I will be able to assist in resolving this issue. I appreciate any assistance in advance.

Best Regards

Thomas.

 

[System Error Message]

This is because windows sees 2 networks. For one of them go to IPV4 properties, advanced and uncheck default gateway. Do this for the ipv6 as well.

 

[shelms488]

This is because windows sees 2 networks. For one of them go to IPV4 properties, advanced and uncheck default gateway. Do this for the ipv6 as well.

Okay, Thanks for the quick reply. Under Connection>Properties> IPV4 Properties>Advanced I see a box for default gateways, and a button to add but no box to uncheck except for Automatic metric. Could you please clarify?

 

[System Error Message]

just uncheck default gateway for the NIC that doesnt go to your router.

 

[coxhaus]

The IP address on the PC and the Synology is bad. DHCP is not working. You can not use 169.254.xxx.xxx. The 169 IP address is a registered IP address. You can not go on the internet with somebody else's IP address. You may just need to assign static IP addresses to your second network or create a second network scope for DHCP. I don't know if your router support multiple DHCP scopes. Plus it's late, I'm tired and I don't want to map all this out so post a diagram.

PS
What are you trying to accomplish with the second network?

 

[shelms488]

The IP address on the PC and the Synology is bad. DHCP is not working. You can not use 169.254.xxx.xxx. The 169 IP address is a registered IP address. You can not go on the internet with somebody else's IP address. You may just need to assign static IP addresses to your second network or create a second network scope for DHCP. I don't know if your router support multiple DHCP scopes. Plus it's late, I'm tired and I don't want to map all this out so post a diagram.

PS
What are you trying to accomplish with the second network?

Thanks for your replies. First to @System Error Message I think the issue has resolved itself. I had the default gateway on both the Synology and the PC for their respective network adapters set to blank. I restarted a few times and it seems to have cleared up. Thanks for the info.

Second, @coxhaus I am using the Synology NAS as a Storage setup for my mass storage needs, mainly all my BluRay movies. and I have PLEX Media server running on my PC. I want the computer and NAS connected to my home LAN via the switch and I have a direct connect via crossover cable between the NAS and my PC/Media server for the fastest connection. I do want to point out that the network using the 169.254.x.x address space is a local only connection, not a WAN connection. Furthermore the 169.254.x.x/16 address space is reserved by Microsoft for Link-Local addressing or a segment that isn't meant to connect outside of it's segment. So it is perfect for my needs. Also, they are both static IP's as I wanted them to never change.
Please see attached network Diagram.

 

[coxhaus]

You need to change your IP addresses from 169.254.xxx.xxx to a private IP address. The 169 IP address is owned by someone. You have a choice of private IP addresses 10,172, or 192. Please use them. Using someone else's IP addresses and trying to not let them out on the internet is bad form.

PS
Just assign a valid private IP addresses to your second NICs without a gateway if that what you want to do.

 

[tim]

The 169 IP address is owned by someone

Nope. https://en.wikipedia.org/wiki/Link-local_address

 

[coxhaus]

I stand corrected. It was changed 2005. I guess I am getting old and out dated. Thanks for pointing it out Tim.


As long as you don't use a default gateway your traffic should stay local.