Unfortunately factory reset did not clear the problem. Serial number is SM_A105 FN
Problem occured at two specific locations even after reset. The wifi networks did not show on my phone however my girlfriends older Samsung phone did pick them up.
In that case as @Qwerty7 said, the problem persists because of the different connectivity specs between the two phones.
All the Galaxy A5's support the 2.4GHz and 5GHz frequency, while the A10 only supports 2.4GHz.
Also make sure, that the LAN protocol is matching with the device (802.11 b/g/n).