Currently there are direct flights from Ibiza to Portugal:

Ibiza to Lisbon

Flights from Ibiza to Portugal with one stopover.

Flights via Barcelona (BCN)
From Ibiza (IBZ) with Vueling Airlines
OR
From Ibiza (IBZ) with Iberia Airlines
Transfer at Barcelona (BCN) Then on to Porto (OPO) with Vueling Airlines
OR
Then on to Porto (OPO) with Iberia Airlines
Flights via Madrid (MAD)
From Ibiza (IBZ) with Iberia Airlines Transfer at Madrid (MAD) Then on to Porto (OPO) with Iberia Airlines
Flights via Amsterdam (AMS)
From Ibiza (IBZ) with KLM Airlines Transfer at Amsterdam (AMS) Then on to Porto (OPO) with KLM Airlines
Flights via London Heathrow (LHR)
From Ibiza (IBZ) with British Airways Transfer at London Heathrow (LHR) Then on to Faro International (FAO) with British Airways
Flights via Palma – Majorca (PMI)
From Ibiza (IBZ) with Air Berlin Airlines Transfer at Palma – Majorca (PMI) Then on to Faro International (FAO) with Air Berlin Airlines
Flights via London City (LCY)
From Ibiza (IBZ) with British Airways Transfer at London City (LCY) Then on to Faro International (FAO) with British Airways
Flights via Cologne (CGN)
From Ibiza (IBZ) with Germanwings Airlines Transfer at Cologne (CGN) Then on to Faro International (FAO) with Germanwings Airlines
Flights via Frankfurt am Main (FRA)
From Ibiza (IBZ) with Lufthansa Airlines Transfer at Frankfurt am Main (FRA) Then on to Faro International (FAO) with Lufthansa Airlines