@Ve10 If your EE Smarthub+ is working fine in the home, then the Fibre side is good, it has nothing to do with the networking side off the operation. The cat 6 cable that you have, it plugs into the back of the EE Smarthub+ Lets use port 1, Port 4 is the connection going to the ONT and is marked also as WAN on it.
The other end off that Ethernet cable in your remote office, is going to connect to the Tp-Link 5 port switch so can you say which switch you have, i always recommend the TL-SG105S as i know that it works well with the + Router. That cable plug it into the very right hand connection on the switch, there is a little green light on the switch it will light up, shows the cable is good and the Router/Switch are both connected. There is a 30 second delay as the switch/router connect to each other so allow that to happen!
The four remaining ports 1 to 4 left to right are now available for connecting your devices, start off connect the PC to No1, again green light will come on, and at this point open up a browser type http://192.168.1.254 and the web manager will open up, the status page should open up, network to right i think click on it and it will give you an over view of the ports and wireless connections! Port 1 will have the number 1 in it as that is the office PC, the more you add the number will rise for connections on that port!
If nothing works, laptop will be needed to go back to the Router short cable remove port 1, connect LT/EE together wait the 30 seconds for the connection to happen then http://192.168.1.254 again to see and check works port is ok, plug back the cables, goto the other end of the long cable plug back into the laptop wait the 30 seconds again rinse and repeat until you know what is falling over! All eight cores on the cable are needed for the 1Gb/s speed, but only 4 are required for the speed to drop to Fast Ethernet at the 100Mb/s range. If the switch does not connect then SW issue!!!
Happy testing!👌
