Servers %>%
  group_by(Server) %>%
  filter(
    all(c("021-08183", "79P-01747") %in% Product) & (Product != "021-08183")
  ) %>%
  ungroup()

# A tibble: 15 x 2
   Server    Product
   <chr>     <chr>
 1 AUSTRALIA 79P-01747
 2 AUSTRALIA C5E-00746
 3 AUSTRALIA 7NQ-00302
 4 AUSTRALIA 7JQ-00341
 5 COLOMBIA  79P-01747
 6 ECUADOR   79P-01747
 7 ECUADOR   6QH-00002
 8 COREA     79P-01747
 9 COREA     #N/A
10 COREA     6QH-00002
11 BRASIL    79P-01747
12 BRASIL    76P-00742
13 ALEMANIA  79P-01747
14 ALEMANIA  C5E-00746
15 ALEMANIA  7NQ-00302

Servers %>% group_by(Server) %>% filter(if(all(c("021-08183", "79P-01747") %in% Product)) Product != "021-08183" else TRUE)