Note: Network Engineer work is to install routers/switches nationwide for interconnectivity of branches and data servers.
بسم الله الرحمن الرحيم
Perhaps, a network engineer is entitled to write or check interest based accounts, rather he is responsible to connect server with other machine as an engineer, if he does only such type of work, then apparently such a job is lawful. But since the banks operate on interest money and the salary one gets is from the same category, therefore it is preferable to look for any lawful job.
Allah knows Best!
Darul Uloom Deoband