I am sure there are plenty of people that know far more about networks than I do, so I would appreciate any troubleshooting ideas people may have. I recently switched my ISP from Cable to Fiber optic, but as I already have my internal wired and wireless neworks set up, I just wanted to swap the Cable Modem for the Fiber modem. As I don't have an option, I was given a ZTE fiber modem/router. There is only one place where I can fit this (due to cabling etc) and it is located below in my media cabinet below the TV. This is not a good place for Wifi, so I installed the fiber router there and ran a Cat6 to my other router that provides me with Wifi. My old network (which worked fine) was set up as follows. Cable Feed (TV+internet) > TV/Internet Divider > Cable Modem (192.168.30.2) > TP Link Router (192.168.30.1) > HP Procurve Gigabit Switch > Various Rooms and devices (including Satellite box 2) My Router was providing Wifi to all wireless devices (on mixed a/b/g/n using channel 11 due to local traffic). All wired devices were issued with IPs betweem .10 and .50, and connected either to the router or to the HP Switch. DCHP was limited to IPs between .100 and .200. So, my new network is like this: Fiber optic feed > ZTE Fiber Router (192.168.30.2) > Satellite Box 1 + HP Switch + TP Link Router (192.168.30.1) > Main PC and Wireless Devices First I turned DHCP off on the Fiber Router and left the TP Link Router assigning .100 to .200. I made the main gateway 192.168.30.2 on all devices that would let me do so. This caused some devices to connect via wifi and other would not, even two phones of the same make and model (one would, the other wouldn't). Also, Satellite Box 1, which was connected directly to the Fiber Router, would not connect with a fixed IP, however, Satellite Box 2 (same make and model) connected to the HP Switch and then to the Fiber Router worked fine with a static IP. The only way I could get Satellite Box 1 to connect was by activating DHCP on the Fiber Router. So, I let the Fiber Router assign IPs between .50 and .99, kept the TP Link assigning .100 to .200, and made sure that all wired devices with static IPs were between .10 and .49. I also switched the Fiber Router to .1 and the TP Link to .2. This cleared up the Wifi connectivity with the devices that wouldn't connect before, and also made Satellite Box 1 work, for a while. After a week or so, the Sat Box stopped working and the only way to get it back online was to switch from Wired to Wifi connection. Then this also stopped working a few days ago, it will no longer connect via cable or wifi. Other erratic behaviour is various laptops and phones just seem to freeze and not load webpages although connected and with full wifi coverage. It is not an ISP problem, as my main PC (connected to the TP Link and then to the Fiber Router) shows download speads of 299MB and upload of 45MB constantly, even when other devices will not load. I have made sure that no devices have IP confilcts and that all are addressed correctly (I did have to set the primary and secondary DNS on some of them for them to work), I have checked the routers responses during these freezes from other devices and it responds fine, no hang ups. Also, if I connect any of the devices that are refusing to respond to my mobile hotspot, they immediately respond again. This also goes for Satellite Box 1, if connected to my mobile hotspot, it works fine. Can anyone suggest what to try next?