乗り換え and 経由: changing vehicles and traveling via a place
Distinguish changing transport from following a route through a location.
Changing vehicles
乗り換え (のりかえ) means a transfer between vehicles or services. 「乗り換えに十分かかります」 says the transfer takes ten minutes.
「次の駅で乗り換えます」 places the transfer at the next station. The transfer point need not be the final destination.
A route via a place
経由 (けいゆ) means going via a place. 「大阪経由で行きます」 says the speaker will travel via Osaka.
「この経路は港を経由します」 says the route passes through the port. It does not necessarily establish a vehicle change there.
Count versus route
「乗り換えは一回です」 gives one transfer. It does not limit the journey to one stop.
「経由地は同じですが、乗り換えの回数が違います」 says the via point is the same but the number of transfers differs. Keep the facts separate.
Does 経由 guarantee a transfer at that place?
Show the answer and why
No. It identifies a route via the place; changing vehicles is separate information.