This one has me tearing my hair out.

We have a couple of Internet connections in our office to provide WiFi to staff (completely separate from the corporate network) and for guests.

One is a 100Mbs connection to DTS. The other is Vodafone UFB.  The DTS connection will be disconnected once UFB has proved to provide our needs.

Both connections terminate in a Mikrotik router with the router configured to handle UFB. Nothing special needed to be done for the DTS connection since it's basically a 100Mbs Citylink connection.

The outbound ports on the Mikrotik go to small switches off which hang a number of AP's (mainly Netgear with one Linksys and Belkin).

The Mikrotik is set to do DHCP etc so the AP's connect via their LAN ports.

Everybody has no issue with connecting to the Internet on the Vodafone UFB connection, except with my Nexus 5. This device can access all of the AP's,  can ping the DNS servers and other sites via IP but cannot access the Internet. Clearly DNS is not being resolved on the phone. I have even tried putting in the IP address of some sites but no access. The phone has no issue on any other AP's (such as at home). Even my Nexus 7 (2013) can connect fine. 

I have done the obvious things like forget the AP's, add them back, do manual DNS entries to no avail. I haven't done a factory reset which I am reluctant to do given it works fine on all other AP's. The phone is on 4.4.3 which occurred the other day but the problem was in existence before that.

But what makes it even more puzzling is, if I reconnect one of the AP's into the DTS Internet connection, the phone connects to the Internet fine via that AP.

Anybody with any thoughts on how I could resolve this?

I have no other N5 to test with. 

 

 

 

Thanks