Hello Networking geniuses. I'm having a very frustrating issue and I hope someone can point me in the right direction. Also, If these is posted in the wrong section, I apologize profusely, and please feel free to move it to the right section. I don't want to step on any toes.
So this past week I built out 6 Windows 8.1 pro workstations and installed them in a local business. I'm using a Watchgaurd XTM 26 appliance as the router, and there are only about 12-15 total devices on the network. All of the computers are identical in every way, and, if necessary, I can post a PCpartpicker list of the components I used. All I did was build it out, install the drivers on the disk (drivers only, no software), and install an Anti-virus and Microsoft office.
Every computer went in perfectly, and are connected to the internet with no problems..... except one.
The network is laid out fairly simply: The ISP Gateway into the router, then out to a 24-port switch, then from there to each device on the network (including one AP which is used for staff to connect their phones)
This one computer will connect to the network no problem (hard wired connection btw), pull an IP from the router, and have internet access upon boot, but that will only last for 5-10 minutes and then I will lose internet connectivity. Internet connectivity can only be restored by a restart. Sometimes I'll get connectivity randomly back, again for 5-10 minutes before it drops again. Also, all of the other computers say the connection's name, let's call it "Business," but this particular computer says "Network."
What I've tried so far:
The absolute first thing I did since the build was so new and we were using SSD's is I just formatted the hard drive, and reinstalled everything again. When the problem continued, I went online and got the latest driver from Realtek for the integrated NIC, but no change. I then inspected the cabling, and replaced two parts of it (there are 4 cables between the switch and computer. Switch to patch panel, panel to keystone in the office, and patch cable from jack to computer), but even when I'm unable to get internet access, I can still access the NAS and some other mapped drives. Whether the connection is working or not, I still pull the following when doing ipconfig:
So I had a USB 2.0 to 10/100 ethernet adapter lying around, so I put that in and installed the drivers and tried that connection, but the problem remains. (I've been doing ipconfig /release and /renew this whole time just fyi)
When the internet is down, I can't ping any websites in cmd OR the router, although I can reach other devices on the network. I've even disabled Windows and the Antivirus firewall, but, like I said, all of the other computers on the network are EXACTLY the same in every way and are all working perfectly.
The only two things I can think to do:
Try using a wireless adapter to see if there is any difference
Re configuring the router/firewall (I don't really think this would do it either because when I lose connectivity it won't even ping the router?)
Also, I get no connectivity if I try and input a static IP address on the router.
If anyone has any suggestions of some things to try it would be great. I'm sorry I didn't include any logs with this post, but it's Sunday and i don't have access to the computer until tomorrow morning. I just wanted to see if I could show up tomorrow armed with a few more things to try to resolve the issue. I appreciate you taking the time to read this long post.