Student interactions in physics laboratories are critical for learning, yet prior research has largely focused on peer exchanges while overlooking the instructor’s role within classroom networks. Here, we examine advice-seeking interactions using a longitudinal social network design with 98 engineering students across ten laboratory sections in two public universities, distinguishing ties within lab groups, ties across groups, and ties directed toward the instructor. We analyze tie strength, intensification, weakening and invariance in relation to students’ self-efficacy and network position, measured through average in-strength. The dyadic network included a total of 1009 directed ties. Descriptively, student–instructor ties showed high average weights from pre- to post-test (2.44 to 2.67), a similar trend observed in within-group ties (2.33 to 2.77), and cross-group ties remained weaker (1.52 to 1.44) from the beginning to the end of the semester. Model results indicate a layered advice-seeking ecology: Within-group and instructor-directed ties showed higher intensity at both measurement waves, while cross-group ties were more numerous but weaker. Self-efficacy is associated with selective targeting rather than greater overall interaction intensity: students with higher self-efficacy report stronger ties to actors who are, on average, more intensively sought for advice, including the instructor, and the odds for the intensification of advice-seeking relationships among students from the same group over the semester. These findings extend peer-centered accounts of classroom networks by showing that help-seeking in undergraduate physics laboratories is organized through a layered advice-seeking structure, combining focal instructor and lab-group ties with a more weaker layer of cross-group student interactions.