So for years I have had my VM superhub 3 in modem only mode, and use my Asus RT-AX88U for DHCP and Wifi etc.Connected to the Asus router I have a couple of Netgear GS308 switches, and everything plugged into them, via Wifi, or directly plugged into Asus router. Internet and download speeds all work fine.
Recently (sorry for long description) noticed a few devices no longer connected to network, noticeably a TP-link powerlink (was being used to boost Wifi into sons bedroom). This plugged into one of the Netgear switches, and appears to refuse to pickup a IP address from the DHCP server, instead using a different range (in the 192.168.0.x range). Tried different cables and trying different ports on the same switch and the other network switch, and still it would not pick up a valid IP address (the powerlines worked, and I could connect to its Wifi, currently using a different Wifi name to rest of the house) but it (and any devices connected to it) had no internet connection. The only thing that worked was plugging the powerline directly into back of Asus router, which was not practical as it sits on a shelf above the Kitchen door (kinda centre of house) whilst the switches and Superhub are under the stairs. I tried using the powerline in dynamic mode (i.e using the Asus DHCP) and manual mode setting a IP address that could be set by the DHCP server, and set a IP rule in the Asus router to always give the device the same IP address)
I thought it was maybe a problem with the SuperHub modem mode somehow (i.e the superhub not quite being in modem only mode properly and maybe somehow using its own DHCP server). So I followed the guides on this site to put it back into router mode (with Asus router unplugged), followed the 4 steps to put back into modem only mode, rebooted it, powered up the Asus router, let it sort itself out and then plug that into the SH. Problem still persisted. Anothr issue is that before and after the reset I can no longer access the suberhub using the modem only mode IP address (192.168.100.1). I could access the superhub whilst it was in router mode just fine though. No idea how long that's going on for, but it makes me think the hub is somehow interfering with my network, although I have no idea how?
Any thoughts on why hub can't be accessed in modem only mode, and why certain devices refuse to pickup up a valid IP address from the DHCP server? (DHCP uses 192.168.1.x range). As a further test, I tried using another network cable on our Xbox One which usually connects via Wifi fine, and it also appears to be doing same thing as the powerline, and which is also plugged into the switch with a long cable under the floor boards. A DVD player, and a TV upstairs also do same thing - all plugged into one of the switches, and usually use Wifi, which is why I have not noticed before.
Searching online I can various instances of bad cable's, and dogey switches (one id new from last year), but can't find examples of certain devices refusing to connect regardless of what switch port they use!
Thanks in advance for any help ;-),
meadwak
