Broad-band SED modelling for IFRS, using the FIR flux density upper limits measured in this work (red arrows), SERVS/SWIRE near- and mid-IR flux density upper limits (black arrows), and the detections at 1.4 GHz (black bar). The template SEDs were shifted to redshifts between z = 1 and z = 12. Shown are the results at z = 1 (upper left subplot), z = 4 (upper right), z = 8 (lower left), and z = 10 (lower right), respectively. The legend shown in the upper left subplot is valid for all four subplots. At redshifts z ≲ 5, no template is in agreement with the photometric constraints of IFRS. However, if shifted to the redshift regime 5 ≲ z ≲ 8.5, Cygnus A (orange solid line) is in agreement with all constraints. The spiderweb galaxy (black dashed line) provides an appropriate template if shifted to very high redshifts z ≳ 10.5. The CSS source 3C 48 (blue dotted line) and the RL quasar 3C 273 (magenta dashed-dotted line) fulfil the constraint in the radio regime at redshifts 6 ≲ z ≲ 9 and 8 ≲ z ≲ 12, respectively, but disagree with the 3.6 μm flux density upper limits at these redshifts.