Yes, this could be a network issue. A slower connection can drop. Your internet provider could have download limits. Other connection issues are possible but those are two most common reasons we have had reported when this has come up before.
Try adding this argument to your wget string: -c
For more explanations, Google “resume curl” or “resume wget” for much discussion. Plus, the man page for each tool will have official argument descriptions. Both can resume but in slightly different ways that can also differ by OS. You’ll need to test what works for you. If none work, confirming what your IP provider data transfer/time limits are is the next step.
Example, this Q&A gives a good line-liner to "resume transfer for curl".