I have a domain and website that is 6 months old, started doing SEO on it about 3 months ago. Lately, I started pushing PBN and SAPE hard on it, but it seems like website is stuck at all. Max position for main keywords on SERPs is #30, it never pass that page 4 to page 3 or so, it just seems like it is stuck and cannot move, no matter if I add TF40+ links. So, do you think it is kind of penalty or simply "sandbox" where I should wait few more weeks to get out of it? Btw, I am in medium/high competitive niche, currently about 50 extremely powerful (TF35+) PBN/SAPE links on it. With other domains, I usually rank them without problem, but do not know what is with this domain.