WiFi issues throughout house

[Penetros]

I've had longstanding wireless issues throughout my time in my current residence.

Modem: ARRIS TG862G
Router: Linksys EA6500v2

My currently problem involves connecting with a TRENDnet TEW-713RE device, this device has caused me problems for a while now, but now it's constantly pulling an invalid IP (169.x.x.x). I have the device 3 rooms away, with an ethernet cord going from that device into the desktop computer it handles, I cannot reach the firmware of that device, I've attempted flushing, reregistering DNS and resetting winsock, all to no avail.

I have problems basically in almost every other room, this is a townhouse so I'm not sure if it's other networks nearby causing me issues or just the walls, even in the room directly below it it causes issues. I'd love any suggestions for either a better way to connect other devices or a wireless booster that won't be a hassle to setup, I do have a linksys E900 laying around, but I'm not sure if it's possible to set that up to work like a booster instead of a router.

 

[Tradesman1]

Have you reset the firmware of the Router - the Modem receiving the signal often is 192.168.0.1 and many set the router to like 192.168.10.1 and then devices from there i.e. 192.168.10.5 or 6 or 7 or............

 

[Penetros]

I have not done so no. The default dfg I have set is 192.168.1.1 which I've never changed, I don't have any devices pulling up a specific LAN IP (Will this help?). I do have it set to automatically update the firmware, but it seems it simply checks them for me and doesn't apply them (thankfully, I'd hate to be interrupted working from home). I'll apply this new firmware update now.

If I should reset it and change the DFG I'll certainly do so.

edit: Something I just tried that I hadn't before, since I've got it and did the standard setup I had it running both the 2.4 and 5, and since it default that way, with the same name. I figured I'd try changing them up, and did, and when I connect to the one that is only 2.4, it now is getting much better connection, I will give it a day to see how it fairs barring any other advice for things I should try that will help.