Algumas sugestões corretivas e de avanço de vocabulário:
I've been working in I.T since 2011, so I have 6 years of experience in this field. I started as a help desk ( MANAGER/ASSISTANT/TECHNICIAN,etc? ) and my job was to provide technical support to end-users via phone and online chat. AFTERWARD, I worked as a Network Administrator AND my tasks WERE (to < DROP IT!) also TO provide ON DEMAND technical support, YET ON THAT OCCASION in person; BESIDES, I had to manage the network.
ULTIMATELY, my last job was as A Network Analyst and my DUTY was to configure ROUTERS and SWITCHES, remotely !