Orbi SRR60 (with 3 satellites): loss of internet connectivity

Setup: SRR60 — Orbi Pro AC3000 WiFi 5 Tri-Band WiFi Router; Orbi router connected to modem of the internet service provider, 3 satellites are connected to router, has worked very well for 4 months (note: firmware not updated since purchase!)

Problem: sudden loss of internet connectivity

Observations: modem of the internet service provider is online; able to connect the router from the internet service provider and succesfully gain internet connectivity; restarting modem did not solve the problem, restarting the Orbi router did not solve the problem, resetting the Orbi router did not solve the problem either.

What steps should I take to solve the issue?

Thank you.