Additional Study Information: This trial is testing two experimental drugs for HIV called VH3810109 (also called N6LS) and Fostemsavir (FTR). This trial is a Phase 1b study testing whether these drugs are safe to use in people and can be taken comfortably, as well as whether they may be helpful in eliminating HIV from the body. In this study, FTR will be given as a "helper drug" in addition to VH3810109. We think that, given together with VH3810109, it may help the immune system better recognize and kill cells with hidden HIV, thereby reducing the HIV in "reservoirs" within the body. You may be eligible for this study if are between the ages of 18 and 70, have diagnosed HIV-1, and weigh between 110 and 253 pounds. You may not be eligible for this study if you are pregnant or breastfeeding, acquired HIV via perinatal transmission, or have certain medical conditions. Study participation will last up to 15 months across 9 planned study visits. Participants will be in one of three study arms, who will take either a regimen of traditional antiretroviral therapy (ART) only, ART with VH3810109, or ART with VH3810109 and FTR. Participants will be asked to visit the clinic on schedule, give blood and urine samples, have medical assessments performed, answer questionnaires, and tell the study staff about any changes to their health and medications.